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AIR SICKNESS: 



N;?itore and Treatment 



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AIR SICKNESS 

Its Nature and Treatment 







Bale's Medical Books and Journals 

AIR SICKNESS: 

Its Nature and Treatment 

BY 

RENE CRUCHET, 

Professor of Medicine in the University of Bordeaux 
AND 

RENE MOULINIER, 

Naval Surgeon ; sometime Professor of Naval Hygiene in the 
University of Bordeaux 



With a Preface to the French Edition by Dr. V. Pachon, 
Professot of Physiology in the University of Bordeaux. 

And an Introduction to English Readers by 
Wing-Commander Martin Flack, M.B. 



Translated from the French by J. Rosslyn Earp, M.A., M.R.C.S. 

O 




LONDON 

JOHN BALE, SONS & DANIELSSON, Ltd. 
83.91, great titchfield street, oxford street, W. I. 



I9S0 



VUa" OTIA^IAM 



TABLE OF CONTENTS. 

PAGB 

To English Readers, by Lt.-Col. Martin Flack, C.B.E. vii 

Pkbface, by Professor V, Pachon »x 

Foreword xiii 

CHAPTER I. 

The Physiology of Flying before the War. 

Ascent 3 

Descent 5 

Landing 6 

Study in arterial tension 8 

Pathogenesis II 

Discussion and Summary 12 

CHAPTER II. 
The Physiology of Flying since the War. 

General impressions l6 

Physiological phenomena l8 

Ascent l8 

Descent 24 

Landing 28 

CHAPTER in. 
The Nature of Air Sickness. 

Arterial hypertension 31 

Fatigue. Criteria of fitness 35 

Cold S3 

Mental strain 56 

Emotion 56 

Oto-rhino-pharyngeallesions 58 

Speed 61 

Other factors 63 

Discussion and conclusions 64 



TABLE OF CONTENTS 



CHAPTER IV. 

Training and Overwork in the Airman. 

Physical overstrain 

Cardiac asthenia 

Psychical overstrain 

Airneurosis 



PAGE 

• 73 
. 74 

• 79 
, 8i 



CHAPTER V. 
Air Hygiene. 

The hygiene of the airman 

General advice 

The Principal Contra-indications to Flight. 

Cardio-vascular . . . 

Pulmonary 

Auditory 

Digestive 

Neuro-psychic 

The place of the disabled in aviation 



86 
89 

90 
91 
93 
93 
94 
95 



VI 



AN INTRODUCTION TO 
ENGLISH READERS. 

By Wing Commander Martin Flack, 
C.B.E., M.A., M.B. 

Director of Medical Research, Royal Air Force. 

To a far greater extent than is generally realized, 
a successful future for aviation depends upon the 
mental aptitude and physical fitness of the personnel 
engaged in flying. Investigation has shown that 
many flying accidents are due to what may be called 
the human element. For this reason, it is impera- 
tive that special methods shall be employed in the 
selection and care of the airman. Not only must 
the candidate for aviation possess the necessary 
mental aptitude, but he must also have the potential 
ability to acquire the mechanics of flight. Further- 
more, he must also be endowed with resistance to 
the fatigue, both bodily and mental, necessarily 
associated with learning to fly, with flights of long 
duration, and with flights at high altitudes. 

Given proper selection, the medical care of the 
flier is therefore largely preventive. It is the duty 
of medical officers to watch over their flying per- 
sonnel, to see how pilots are withstanding the effects 
of flying, and to take proper steps to combat at an 
early stage the onset of flying stress, and to mitigate 
its effects. For this reason, periodic medical 
examination, as required by the International 
Aeronautical Convention, is a necessity. It is im- 
portant, therefore, that medical officers shall be 



Vll 



AN INTRODUCTION TO ENGLISH READERS 

thoroughly cognizant, not only of the methods 
employed in their own country, but also of those 
in use in various other countries. They should also 
be acquainted with the progress of research into 
the various medical aspects of aeronautics. On this 
account, the publication of the valuable work of their 
French colleagues is particularly opportune at the 
present time. 

There is still a wide field of investigation open to 
medical officers interested in flying; such work will 
do much, not only to further medical knowledge, 
but also to advance the success of aviation, both 
military and civil. 

Medical Department, 
Air Ministry, 

March, 1920. 



Vlll 



PREFACE. 

All progress is at a price ; man pays a ransom for 
each of his adventures. The conquest of the air, 
besides its numerous dangers, is to-day resulting in 
a new disease, the disease we call air sickness. 

Messrs. Cruchet and MouHnier gave to it a 
precise definition in 1910-11. Aviation was at that 
time making its first great debut, and credit is due 
to these authors in the first place becaus-e they saw 
at once that, if there should happen to be disturb- 
ances pecuhar to aviation, they would be best 
detected during these early flights and before 
assuetude should have had time to play its part. 
In this respect their work was the result of judg- 
ment rather than of opportunity. Through reason 
they foresaw and time has blessed their observation. 

In addition they spared no pains to analyse 
experimentally those peculiar disturbances which 
they observed. Here again it seems likely that their 
analysis must remain as the foundation of the 
pathological physiolog-y of the airman. 

Having directed their researches especially from 
the point of view of the changes observed in 
arterial tension — and many observers seem to have 
copied their example — Cruchet and Moulinier were 
from the first struck by a remarkable phenomenon 
constant in athletic individuals and quite charac- 
teristic after flights in high altitudes. This was an 
observation on landing after flight : a condition of 
arterial hypertension remarkable for the constant 
rise in minimal pressure, with no corresponding 
increase of the maximum pressure. On the contrary, 
a distinct fall of systolic pressure is the general 

ix 



PREFACE 

rule. This constant rise of minimal arterial 
pressure appears therefore to be a vasomotor 
phenomenon. But what is the first cause of this 
intense and general vasoconstriction? Above all 
it is important to know whether this phenomenon 
should be merely recorded along with others, or 
whether it may not be of basic import, controlling 
a whole series of secondary extra-physiological 
reactions. Here indeed is the problem which lies 
at the heart of this little book, to the solution of 
which the authors have brought a distinctly original 
contribution. It will be seen how Cruchet and 
Moulinier have been led to attribute to the question 
of speed in the course of flight (speed in getting up 
and, above all, speed in the descent) not only an 
important but a preponderating place in the genesis 
of various reactions. The perusal of their work 
will also, I think, justify the belief that the state 
of arterial hypertension, or better, of vasomotor 
hypertonia, normally observed in the airman, repre- 
sents something quite other than a simple pheno- 
menon to be added to a catalogue of observations. 
This increase of vasomotor tone constitutes in 
reality the fundamental phenomenon on which 
depend the multiple disturbances in the domain of 
the nervous centres. Dizziness, headache, drowsi- 
ness, the triad symptomatic of a profound cerebral 
vasoconstriction, are here its various expressions. 
Certainly there are cases in which the arterial 
hypertension is wanting, or to speak more correctly, 
it appears so to be, for Cruchet and Moulinier have 
shown that this paradox is only apparent. In 
reality the slightest lowering or raising of the 
minimal pressure expresses a particular thing: the 
fatigue of the airman. The pages of this book 



PREFACE 

devoted to fatigue, and particularly to the means of 
determining its presence in the airman, contain 
many very striking passages. We possess to-day in 
the systematic study of the variations of arterial 
pressure resulting from measured output of energy 
a true criterion of the training- and of the functional 
value of an organism for the production of work. 
When the individual is " in training/' the methodical 
study of his arterial pressure, taken at regular inter- 
vals in the course of work, shows the existence of 
a work plateau, expressing the adaptation of the 
subject. If the latter is not adapted, the fall of 
pressure (and especially of the maximum pressure) 
is equivalent to a real danger sign, which indicates 
the cardio-vascular breaking point; that is to say, 
it constitutes a precise objective sign of fatigue, 
independent of any personal equation. Cruchet and 
Moulinier have shown by abundant evidence how 
such a criterion of "training" mJght be made use 
of with great profit for estimating fatigue both in 
the case of the airman and in various sports. As 
they themselves say, the recent researches of 
Villemin confirm their own in this respect. 

And finally, Messrs. Cruchet and Moulinier have 
drawn from this scientific study a right conclusion : 
a code of practical applications, determining the 
hygiene of the airman and the contra-indications to 
indulgence in flight. Thus their work becomes prac- 
tical. It is apparent that physiological analysis 
pursues the observations of facts, not only to under- 
stand them, but also and more especially to control 
them, or as Claude Bernard would have put it to 
translate them into deeds. 

This little book is a deed. 

Victor Pachon. 



XI 



FOREWORD. 

The researches on the physiology of aviation 
which we undertook in 1910-1911 have roused a 
certain amount of interest, hoth in France and 
abroad, since we made our communication on 
" Air Sickness '' to the Academie des Sciences in 
April, 1911.^ 

Described in the first place by the present writers, 
air sickness has rapidly acquired a place in French 
and foreign literature. It is commonly to be found 
described in pre-war writings under the names of 
El Mai de los Aviadores, in Spanish-speaking 
countries; La Malattia degli Aviatori or // Male 
degli Aviatori or Di Pegaso, in Italy; Mai dos 
Aviadores y in Portugal and Brazil; Aviation or 
Aviator Sickness, in English-speaking countries; 
Die Fliegerkrankheit or Aviaiiker Krankheit, in 
Germany. 

Since 191 1 we have observed that the phenomena 
of air sickness, considered under their most usual 
and least serious form, are physiological pheno- 
mena; that is to say, there is nothing morbid in 
these changes which may be experienced by every 

^ Cruchet and Moulinier : " Le mal des aviateurs " 
{Acad, des Sciences April 24, igii, and Journal de Physiol, 
et Pathol. Generate J pp. 388-395, May, 191 1). The first 
notice of this communication appeared in the Journal de 
tned. de Bordeaux on September 18, iQio, and in the 
Gazette Hebdom. des Sciences Med. de Bordeaux on Sep- 
tember 25, iQio. See also articles by R. Cruchet in the 
Journal (Paris, April 25, 191 1), the Journal Medical Fran- 
fais (August 15, 191 1 ), the Revue Scientifique (December 
9, 1911). 

xiii 



FOREWORD 

healthy man who goes in for high flying. Their 
existence must not be interpreted by any means as 
a proof either of physical or intellectual degeneracy. 
On the contrary, they are most commonly found 
amongst airmen of keen mentality, perspicacity and 
judgment. It is not everyone who is aware of 
them, even when they exist, and since they are 
rarely or never all found in the same subject, it 
will be understood that they may pass unnoticed 
in a rapid examination. 

What is important is not so much their existence, 
in itself of little moment and always transitory, but 
the conditions under which the man is liable to find 
himself at the time when they make their appear- 
ance. A momentary loss of consciousness, a sHght 
giddiness, a simple hesitancy in controlling the 
aeroplane, a buzzing in the ears, an instant of 
sleepiness or of languor, are in themselves very 
insignificant, and do not suggest any real failure in 
the functioning of the human mechanism, but at a 
height of 50 metres and a fortiori at a height of 
several hundred metres above the earth, the con- 
sequences of even such slight disturbances as these 
. are to be treated with very great respect.^ 

We shall recall in our first chapter those pheno- 
mena v/hich we described originally before the war. 

In the second chapter we shall study the advance 
made in the physiology of flight since the war, and 
we shall show that experience has completely con- 
firmed our first observations. 

We shall try in the third chapter to unravel the 
real cause of the phenomena which we have 
described. After having pointed out the capital 

^ R. Cruchet : Revue Scientifique, December g, 191 1, 
loc. cit. 



XIV 



FOREWORD 

importance of arterial hypertension, we shall dis- 
cuss the functional value of cold, fatigue, intellectual 
effort, emotion, speed, and other factors of less 
importance. 

Our observations will lead us in the fourth chapter 
to treat of the questions of training and overwork 
and the physical and psychical accidents which may 
result from them . 

Finally, in Chapter V we shall discuss general 
hygiene and the elementary advice which should be 
given to airmen, as well as the chief contra- 
indications to flying. 



XV 



TGRGfTO Uf 



AIR sickness; 

Its Origin and Treatment. 



CHAPTER I. 

The Physiology of Flying before the War. 

Flying requires a physical effort and a constant 
mental strain because it is carried out under con- 
ditions to which the organism was not originally 
adapted. Generally speaking, flights at high alti- 
tudes such as were carried out by airmen up till 
the year 191 1 lasted for a maximum duration of 
45 minutes. A height of 2,000, 2,500, or 3,000 
metres is reached in from 30-40 minutes, and the 
machine rushes from this height to the earth in 
from 5-7 minutes. Chavez, during his tragic flight 
across the Simplon, rose from 880 metres (Brieg) to 
2,100 (Kulm) in 19 minutes. Morane at Le Havr€ 
reached 2,600 metres in 24 minutes, and returned 
in 6 minutes. At Bordeaux the same flier rose in 
22 minutes to 1,500 metres and came down in 5. 
Legagneux at Pau rose to 3,200 mietres in the same 
space of time. Chavez, Legagneux and Morane 
whose feats we have quoted were flying mono- 
planes. On biplanes these high altitudes are 
reached more slowly and require a more prolonged 
effort on the part of the airman. The descent is 

^ Cruchet et Moulinier : " Le Mai des Aviateurs," loc. cit. 



:)0if.u5L'i^t?ri^i3aun 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

made with equal speed in either kind of machine, 
the rapidity depending on the method of returning 
to earth. ^ This method is known under the name 
of vol-planing. It is used because it appears to be 
impractical to effect a landing with the throttle 
partly or completely open on a machine which 
"has no mechanical contrivance to enable a fast 
machine to descend slowly " (Morane).^ Moreover, 
if they made use of their motor in the descent the 
airmen would see their speed increased in that the 
driving power of the propeller is added to the 
action of gravity. 

A high speed in ascending, a vertiginous descent, 
such is the special mechanical condition peculiar 
to flight at high altitudes. 

This condition gives quite a special character to 
the biological effect of these ascents. It is a new 
and important factor added to the action of pres- 
sure variations (760 millimetres mercury on the 
level, 591 at 2,000 metres, 521 at 3,000 metres) and 
to the changes in the chemical composition of 
the air, and to the temperature variations (60-70 
degrees F. on the earth, 45 degrees F. at 3,000 
metres). These being the ordinary factors which 
condition physiological variations, and to which a 
living organism is always subject at high altitudes. 
It is probably this new factor which gives its 
special character to air sickness — an illness which 
we have tried to study during the festival at 
Bordeaux, which took place from September 11- 
18, 1910, in the neighbourhood of Merignac. To 

^ And sometimes on a breakdown of the motor while the 
machine is in the air. 

2 Note by Translator. — Modern machines have a greater 
range of speed. 



THE ASCENT 

this end we were able to follow every day of the 
week the programme of the principal airmen. In 
particular, Naval Lieut. Byasson, Lieuts. Cammer- 
mann and Remy (biplanes), Messieurs Morane, 
Legagneux, Tyck (monoplanes), Bielovucic, Bregi 
and Juillierot (biplanes) were good enough to reply 
to our questions and submit themselves to our 
experiments. Here are the results of the inquiry 
which consfitute our first communication on the 
subject. 

The Ascent. — During the ascent respiration be- 
comes shorter at a height of about 1,500 metres — 
that is to say, at a less height than when rising in 
a balloon; the heart beats faster, but usually there 
is no palpitation; there is, strictly speaking, no 
sensation of nausea or of abdominal distension 
such as sometimes occurs in mountain climbing, 
but there is a slight discomfort which Morane 
attributes to the mental inquietude which one ex- 
periences in so vast a solitude. At about 1,200 
metres difficulty in hearing makes its appearance; 
the hum of the motor becomes dimmed. This 
phenomenon, which is clear enough in dry weather, 
is even more noticeable when the weather is cloudy 
or misty. Buzzing in the ears, although not 
severe, shows itself at a greater height — about 
1,800 metres (Morane). Legagneux has observed 
clickings in the ears at a lower altitude; it is true 
that it was the first time he had risen to so great 
a height, and a passenger who rose in the same 
way the first time to 300 or 400 metres on a biplane 
experienced the same phenomenon; the question of 
assuetude must evidently be taken into account. 
Even considering it to occur at 1,800 metres, how- 
ever, this phenomenon makes its appearance at a 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

lower altitude than that at which it has been 
observed in mountain climbing. No airman ex- 
perienced any dizziness. 

" The view is always very clear," writes Morane, 
''though the rapidity with which objects pass into 
the distance and diminish in size may give a contrary 
impression." Moreover, in fine weather and when 
there is a haze, the sun may be reflected from the 
surface of the mist with such blinding effect as to 
interfere considerably with the control of the mono- 
plane (Morane).^ Another airman experienced true 
visual hallucinations in the course of a long flight; 
every moment he seemed to see the spires of the 
Cathedral of Notre-Dame appearing on his right 
at the time when he was still several hundred miles 
from Paris. 

A slight temporal headache appears in experienced 
airmen at a height of 1,500 metres; in beginners 
it makes its appearance at a lesser altitude. 

Cold becomes rapidly painful above 2,000 metres; 
at Bordeaux this was particularly the case. 

" At Bordeaux," writes Morane, " I was not cold up to 
1,500 metres; above this height the temperature fell very 
rapidly and at 2,000 metres it was certainly in the region 
of — 15° C.2 At the mouth of the Seine the phenomenon 
of falling temperature was much less marked. I can only 
explain it in relation to the time of the year : it was then 
midsummer, and perhaps the warmth was more penetrat- 
ing and reached farther upwards through the atmospheric 
belt." 

Above the height of 1,500 metres an insistent 

desire to micturate made its appearance. 

^ The great difficulty with the monoplane is to avoid 
giving it too sharp an angle of inclination either in rising 
or in descent (Morane). 

2 Airmen did not carry thermometers at this time, 
Morane's estimate is purely subjective and consequently 
must be accepted with caution. 



THE DESCENT 

Above the height of i,ooo metres, and to a greater 
extent above the height of 1,500 metres, voluntary 
movement becomes more nervous, and irregular, 
reflex movements have a greater amplitude (Morane). 
Cold, slight breathlessness which comes on at this 
time, the more rapid action of the heart, the re- 
flection of the sun and the disturbances of hearing, 
to which must also be added the nervous tension 
and fatigue — all these suffice to explain the changes 
in the motor system. 

The Descenti — In the descent the heart beats with 
greater force, but without acceleration. The palpi- 
tations which are felt without delay increase in 
proportion to the rapidity of the descent. It is 
difficult to take account of the respiratory changes 
on account of the rapidity of the speed of vol- 
planing in which 300 or 400 metres are coveed in a 
minute. The result is a kind of distress, com- 
parable to the sensation of emptiness which we 
experience in a rapidly descending lift. The buzz- 
ing and whistling in the ears, the desire to micturate, 
tend to increase towards the end of the descent, but 
the phenomena which dominate the situation and 
which increase as the earth; is approached, are as 
follows : — 

(i) A burning sensation; a, flushing of the face 
with a sensation of warmth. There is irritation of 
the eyes, which are injected; the nostrils are moist, 
though there is no epistaxis. 

(2) The headache. 

(3) A remarkable tendency to sleep. So compel- 
ling is this that the eyes will close from time to 
time, in spite of the most determined effort to keep 
them open. Only quite recently there was reported 
the case of a young airman who was found fast 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

asleep in his aeroplane in the open country; when 
he had been awakened he was unable to remember 
in what way he had landed. ^ 

We must add that in this dizzy descent— as an 
experienced airman has remarked— the distress puts 
a strain on the strongest. Momentarily the airman 
is even surprised by fear— a fear which, happily, is 
nearly always very brief; but the thought and the 
picture of death are never absent from his mind.^ 

Voluntary movement is slow and awkward, in 
marked contra-distinction to the physical and mental 
vivacity of the individual. Some airmen are aware 
of this numbing of the wits and of a dullness which 
prevents them from carrying out the necessary 
mechanical actions as rapidly as they would wish. 
Others, on the contrary, are unaware of its 
existence. 

The Landing. — When he lands the airman, how- 
ever energetic he may be by nature, steps from his 
aeroplane with a manifest heaviness; he moves off 
with a firm step, though a little slowly, to his 
hangar a short distance away. But now the buzz- 
ings and whistlings in the ear become more intense 

^ This may be compared with the experience of those 
who have come down mountain sides on the funicular rail- 
way. In the descent of the Jungfrau, for example, it is 
well known that travellers who come down from 3,200 to 
2,000 metres (the little Scheidegg) go to sleep in their 
compartments one after the other, though the journey takes 
no longer than 15 to 20 minutes. Practically everyone 
experiences some buzzing in the ears in the course of this 
descent. 

2 The airman Renaux, landing at Puy-de-D6me on 
March 7, 191 1, found himself confronted by these thoughts : 
" The sinister outline of the mountains rose up before nie," 
he said, " and in spite of myself I could not help thinking 
of the hapless Chavez, who paid for his great victory with 
his life." 



THE LANDING 

than they have ever been up to the present; our 
hero is as though deafened, he hears indistinctly 
those who speak to him, or the applause with which 
he is greeted; sometimes he is seized with giddiness, 
his head swims, and it once happened that an air- 
man fell almost into our arms as he wa§ returning 
to his tent. 

The headache persists not only at the time of 
landing, but for several hours afterwards; the same 
is true of the sleepiness. One of the officials at 
the Bordeaux Meeting attached to a young airman, 
who was flying at great heights for the first time, 
confessed to us that his ward was in the habit of 
sleeping- for five or six hours after his excursions, 
that he gave no reply to those who spoke to him, 
but had a numbed and stupefied appearance, eating 
nothing at meal-times, thinking only of sleep. 

These experiences are confirmed by Vedrines. 

The respiratory movements tend to recover their 
normal rhythm from the time of landing : it is 
otherwise with the circulatory mechanism, on whose 
action we shall lay special emphasis. Cyanosis is 
observed in the extremities: the fingers are blue. 
Wynmalen, who reached a height of 2,870 metres, 
remarks that he could feel the blood running from 
his nails into his fur-lined gloves and the red drops 
moistening his lips.^ Morane never noticed a like 
phenomenon, which, moreover, may be related to 
the low temperature in the upper regions of the 
air which makes the speed of the aeroplane more 
noticeable. This chilling is very painful, and all 
airmen complain of it. We have never seen epi- 

^ P. Bassett-Rivet : "A tire d'aile " [Revue des Deux 
Mo7ideSj February i, 191 1, p. 659). 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

staxis, but we have constantly observed hyperaemia 
of the conjunctiva. The eyes, however, may be 
efficiently protected by appropriate glasses. 

The pulse is slightly increased, the dicrotic im- 
pulse in the radial artery is not well marked. The 
oscillations on the Pachon oscillometer are of small 
amplitude. There is no palpitation. 

Study in Arterial Tension.— Arterial pressure is 
constantly increased at the time of landing after any 
flight at altitudes of from. i,ooo to 2,000 metres. 

Amongst the observations which we have made, 
the following are worthy of remark (they are taken 
at the wrist, using the Pachon oscillometer) : — 



Airman Y. 

Before flying 5.30 p.m. 

Minimum pressure Q cm. Hg. 

Maximum pressure 18 ,, ,, 

Pulse-rate 70 per minute. 

At 6 p.m., after a flight of 25 minutes, during 
which on the 20th minute the height of 1,100 metres 
was registered by the barometer, the following 
observations were made : — 

Minimum pressure 12 cm. Hg. 

Maximum pressure 19 ,, ,, 

Pulse-rate 80 per minute. 

After a flight of 2y minutes, with a maximum 
altitude of 1,500 metres: — 

Minimum pressure 12 cm. Hg. 

Maximum pressure 19 ,, ,, 

Pulse-rate 75 per minute. 



STUDY IN ARTERIAL TENSION 

In the case of another airman, after a first flight 
attaining i,ioo metres, we observed: — 

Minimum pressure gi cm. Hg. 

Maximum pressure i6 ,, ,, 

Tulse-rate 80 per minute, 

and after another flight, reaching to 1,380 metres : — 

Minimum pressure loi cm. Hg. 

Maximum pressure i6i ,, p, 

Pulse-rate 84 per mmute. 

This hypertension, which we have very often 
observed, is the more remarkable in that our 
observations were made upon athletes in perfect 
training, a condition which is essential if useful 
data are to be obtained.^ 

The increased pressure is less apparent in sub- 
jects who are suffering from great fatigue. These 
latter experience severe palpitations and show a very 
marked increase in the pulse-rate (108). This tire- 
some tachycardia, symptomatic of cardiac in- 
sufficiency, was noticed in a young airman who had 
just reached a height of 1,000 metres, after a rising 
flight of one hour's duration (see fig. i, p. 32). 

The increase of arterial pressure is peculiar to 
airmen descending from high altitudes. We have 
never observed it in airmen who maintain a height 
of 100 to 150 metres. 

Thus with Lieut. Z. at the time of departure: — 

Minimum pressure 9 cm. Hg. 

Maximum pressure 19 ,, ,, 

Pulse-rate 80 per minute. 

^ V. Pachon : " Education physique et criteres fonction- 
nels. Les variations de la pression arterielle, critere 
d'entrainement " (Soc. de Biol., May 21 and 28, 1910, 
pp. 809 and 927). 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

On landing after a flight of 55 minutes at an 
average height of 100 metres : — 

Minimum pressure gi cm. Hg. 

Maximum pressure i8i ,, ,, 

Pulse-rate 100 per minute. 

If we must formulate a hypothesis to account for 
these changes in blood-pressure — changes which 
may have a serious sequel in patients subjected to 
a very vigorous mental strain, or to a sustained 
concentration — we should Hke to submit that an 
organism falling in 20, 30 or 40 minutes from a 
height of 1,000, 2,000 or 3,000 metres has not the 
time necessary to adapt his circulatory system to 
the variations of atmospheric pressure (521 mm. Hg 
at 3,000 metres, 591 mm. Hg at 2,000 metres, 
760 mm. Hg at o). The hypertension observed on 
landing is the expression of a vasomotor reaction. 

The disturbances upon which we have remarked 
often show different forms in different individuals. 
In this respect air sickness resembles mountain 
sickness. Some, perhaps, are always free from 
sickness, such as Janssen; some will be affected at 
relatively low altitudes, as Martin de Moussy, who 
experienced *Ma puna "at 1,970 metres. '' Many have 
told me, and I have experienced it myself, that 
they were taken ill at altitudes of less than 2,000 
metres."^ The symptoms may be more or less 
marked, according to individual temperament, but 
speaking generally it may be concluded that they 
make their appearance at a lesser altitude than is 
the case in mountain climbing or even in balloon 
ascents. 

^ H. Kronecker, Revue Scientifiquej January 26, 1895, 
P. 98. 

10 



PATHOGENESIS 

Pathogenesis.— What is the pathogenesis of the 
events which we have described? 

The numerous controversies^ which gave origin 
to the researches on mountain-sickness and on the 
sickness of high altitude do not enable us to form 
any conclusion on the disturbances which we have 
observed, and which in certain respects resemble 
these former disorders. But we have been struck 
by the constancy and the importance of the varia- 
tions in arterial pressure which are evidenced by 
our measurements and by the fact that these varia- 
tions are especially marked after rapid ascent or 
descent to or from high altitudes, whereas in flights 
at moderate altitudes, undertaken by trained pilots, 
there is no clearly marked reaction. 

In conclusion, it is to be noted that vasomotor 
reactions, accompanied by hypertension, dizziness, 
headache, sleepiness, appear particularly at some 
time after landing. It is these phenomena which dis- 
tinguish " air sickness " from '' mountain sickness,'* 
and which give a quite special aspect to these dis- 
turbances. The origin of air sickness is in all 
probability the rapidity with which the airman 
travels in space, and we believe that it is the inter- 
vention of this factor which makes comparatively 
slight changes in atmospheric pressure of serious 
and even dangerous moment. We say compara- 
tively slight, for so they are, in relation to the 
changes of pressure to which divers, for example, 
are subjected, and it is worth noting that the diver's 
troubles (buzzings, dizziness, congestion, haemor- 

1 See the " Remarques " by Zuntz and Loewy, and the 
^ Reponse a ces remarques " by de J. Tissot, in Journal 
de Physiologic et Pathologic Generate, January i, igii, 
pp. I and 75. 

II 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

rhage, &c.) are in some respects analogous with 
those which we have been considering in the 
airmen. 

Discussion and Summary.— Certain objections 
have been raised since the publication of our com- 
munication, as a result of which we have had a 
series of interesting interviews. 

Some of the airmen whom we have interrogated 
state that no such symptoms as described above 
have ever been experienced by them. But most of 
these had never taken part in high flight tests, and 
as a result their experience is not of great interest. 

The disturbances which we have observed were 
always, even in their least severe forms, consequent 
upon ascents to a minimum altitude of 800 metres 
and a rapid descent therefrom. It was only, there- 
fore, such observations as had been made upon 
airmen coming down with great rapidity from this 
height that had any value : amongst those who 
underwent these conditions there were very few who 
had had no experience of symptoms. 

We do not attach the significance of originality 
to those physiological phenomena which accom- 
panied the ascent : they are already classical, having 
been known for a long time by climbers and 
balloonists. They do show in airmen, as we have 
pointed out, this special peculiarity that they make 
their appearance at much lower altitudes than is the 
case either in mountaineering or in the balloon. 
But the aeroplane ascent is too slow and the height 
attained — less than 4,500 metres up to the time 
of the war — was not sufficient for any really 
disquieting symptoms to result. 

Quite otherwise is it with the descent, which is 
dangerous in proportion to its rapidity and to the 

12 



DISCUSSION AND SUMMARY 

height from which it commences. If in the case of 
slow descents the phenomena experienced are 
Hmited to a sHght buzzing in the ears (Legagneux), 
to a sHght oppression, some auditory disturbances 
and excitement (Latham), to a sensation of stopping 
of the ears (Garros),^ these Hmitations do not 
apply wh-en the descent is made at a high' speed. 
Take the case of Leon Morane, who came down at 
Trouville, his motor out of action as the result of 
a break-down, from 2,585 metres in i minute and 
40 seconds, or at a speed of S7i niiles per hour. 
He acknowledged that he had felt faint, languorous, 
that he was extremely fatigued, and had a violent 
headache. All of these symptoms became worse at 
the time of landing when there were added to them 
buzzings and whistlings of the ears which lasted for 
several hours afterwards. Similarly Vedrines con- 
fessed to us that when one day he was obliged to 
come down at Varennes-sur-Allier from 3,000 metres 
in the space of about 3 minutes, or at a speed of 
37J miles per hour, his hands became purple, his 
veins swollen and blue and he experienced a persis- 
tent headache for several days afterwards. 

Although one cannot ascertain definitely that it 
was owing to such phenomena as these that Chavez 
met his death, there are strong grounds for such a 
presumption; the same is true in the case of Hoxsey 
who, at Los Angeles in America, rose to a height 
of 2,300 metres in half an hour, came down again 

1 Garros, who arrived at Bordeaux on January 24, 19 14, 
for an exhibition flight, volunteered readily to submit to 
an examination. On that day he flew scarcely higher than 
700 metres, remaining in the air on each occasion for 
10 to 15 minutes and descended gradually. His pressure 
was the same on landing as at the departure : Mx., 16^-17: 
Mn., 8i 

13 



THE PHYSIOLOGY OF FLYING BEFORE THE WAR 

in 2f minutes, or at a speed of about 31 miles per 
hour and was killed on the spot. No less authority 
than Latham who witnessed the accident, relates 
that 150 metres from the ground the machine was 
seen to turn round and round without any effort 
on the pilot's part to recover himself. '' Everything 
points to the conclusion/* adds Latham, '"^ that 
Hoxsey must have fainted.'* 

There are others who have noticed that accident~§ 
may be due to the airman himself and are not always 
the result of failure in the machinery. 

P. Rogers fell in Cahfornia from a height of 
some 60 metres. He had the good fortune to 
escape alive and related that he had been seized 
vAth sleep at about 350 metres above the earth. 
He added that in spite of the clear consciousness 
of danger, he had been quite unable to overcome 
this somnolence which gradually encompassed him. 
He thought that this ''aerial somnipathy " must 
have resulted in the death of many airmen. 

The same newspaper article relates that Captain 
Madiot met his death in 1910 through a fall at 
Douai which appeared to have resulted from an 
attack of syncope.^ 

Vidart and Vedrines, after they had landed at 
the aerodrome of Ans (near Liege) one Sunday at 
the end of June, 1911, "could not disguise their 
irresistible desire to sleep." The same phenomena 
were observed in the case of Vedrines during the 
Paris-Rome-Turin race. 

It is interesting to notice that immunity to 
mountain sickness confers no immunity to air 
sickness; thus Latham, who had never felt any 

^ Po'pular Science Sif tings, October 19, 1912, pp. 84-86. 

14 



DISCUSSION AND SUMMARY 

symptoms of mountain sickness despite numerous 
climbs in high countries to a height above 2,500 
metres and balloon ascensions to 3,000 or 4,000 
metres, experienced those slight disturbances which 
we have described as air sickness, in coming down 
from a height of 1,500 metres in an aeroplane. It 
is clear, therefore, that the two syndromes ^re not 
identical, and it is for this reason that we have 
especially insisted on the part played by hyper- 
tension resulting from rapid descent. 

To resume briefly, we have always thought that 
air sickness is due to the rapidity with which airmen 
regain the earth from great altitudes. When they 
have taken 20, 30, 40, 50 minutes (Captain Felix), 
I hour 54 minutes (Garros) to ascend, they come 
down again vol-planing in 4, 5, 7, 8 (Felix), or 9 
minutes (Garros), that is at the rate of 300, 400, or 
500 metres a minute, a speed equivalent to from 12 
to 20 miles an hour. Prevost in December, 191 1, 
rose to 3,000 metres in 58 minutes 30 seconds with a 
passenger, and came down again in 7 minutes, or 
at 15 miles an hour. 

The human organism, particularly as regards its 
respiratory apparatus, is not able to adapt itself in 
so short a time to the different conditions of atmo- 
spheric pressure, vai-ying from 520 mm. of mercury 
at 3,000 metres, or 591 mm. at 2,000 metres to 
760 mm. at sea level. Thus, from the time of 
our earliest research it has seemed to us of the 
greatest importance to draw attention to the result- 
ing rapid increase in arterial tension and particularly 
in the minimal arterial pressure. 



15 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 



CHAPTER II. 

The Physiology of Flying since the War. 

War experience, as we shall now show/ has 
confirmed very closely our original work. From 
the outset of this chapter it must be clearly under- 
stood that it is not with the influence of curiosity 
and emotion that we are now concerned, but only 
with the part played in the physiology of flying by 
physiological reactions. 

General Impressions. 

The impressions of one's first flight are delicious, 
exhilarating, unforgettable. Here are the records 
made by one of us (Cruchet) at Toul, on a Septem- 
ber evening of 1915, in a Maurice Farman : — 

I put on my hat, cross the fuselage, climb up and seat 
myself behind the pilot. Round my waist I pass a belt, 
which is securely fastened to the seat behind me. 

The pilot raises his arm. The propeller is swung and 
whirls round with an infernal noise; everything about us 
is flickering; a soldier's cap is blown away; the overalls 
of the mechanics who stand round flap in the strong wind 
which we are making. The blades of grass are flattened 
like a field of corn after a thunderstorm. 

This for a moment only. Now we are off. We skim the 
earth for 100 yards or so, then abruptly we rise. These 
few seconds occupied in leaving the earth are unspeakably 
delicious. There is an exquisite surprise. The warm air 
lashes our faces. There is no shock, no hesitancy as in 
a motor-car; we glide on smoothly with no obstacle in our 
path. 

In spite of the fact that dizziness is said to be unknown 
in an aeroplane, one still hesitates to lean a little out of 

^ Cruchet and Moulinier : " Le mal des aviateurs," Soc^ 
de Biol, meeting of June 21, 1919, pp. ()77-^7^^ and Journ. 
de Medecine de Bordeaux^ July 25, 1919. 

16 



GENERAL IMPRESSIONS 

one's seat and look beneath. There is a momentary sense 
of fear, and already the earth appears 300 or 400 metres 
distant at the first timid glance. This view charms im- 
mediately, and it is quite true that there is no sense of 
dizziness : confidence increases. 

Presently the country stretches out as far as the eye can 
see. The earth is mottled with splashes of light green — 
these are the meadows — and with stretches of dark, green : 
the forests and woods. Elsewhere it is striped with great 
bands of colour, brown or pale, according to the crops 
there under cultivation. Here is a rocky crest, surmounted 
by a fortress; there a village with houses of white stones 
and red roofs. A few surrounding trees throw shadows 
lengthened by the sinking sun. In the valley is the 
Moselle, like some sinuous serpent, reflecting the light 
from its silver scales. The white tracery of the roads lies 
over all. This might be a miniature sheep-fold, such as 
we played with when we were children : people, houses, 
animals, leafy trees, we know them all again as we knew 
them in those far-off festivals at Christmas and the New 
Year. A delicious emotion moistens the eyelids with tears 
of pure joy. 

Towards the horizon the distance melts into the infinite 
blue : one longs to arrive there, always to go farther on 
the way. The day-dream is only slightly disturbed by the 
deafening hum of the motor and the cold which is begin- 
ning to get a grip. The sense of security is extraordinarj^ 
all fear, even anxiety, has disappeared. We seem to grow 
lighter as if drinking air, only the wind whistling in the 
bracing wires tells the speed at which we are travelling, 
and still we seem to stand still. Actually we are moving 
at 50 or 60 miles an hour. 

Now we are lost in immensity ! Only with great diffi- 
culty can I make myself understood by the pilot on account 
of the noise of the motor. From time to time I catch a 
few words that he is obliged to shout. 

Presently the pilot makes a sign to me. I move my ear 
to his lips. " See," he says, " how easy and supple is the 
handling of an aeroplane," and he looses the controls, 
raising his two arms into the air. For some seconds he 
remains thus and then takes control again. A little 
nervousness on my part does nothing to lessen my growing 
wonder and enthusiasm. We are more than 1,000 metres 
high, when suddenly he signals to me again. I draw near. 
" Now look out," the pilot says ; " hold fast, we are going 
to descend." 

I sit solidly in the depth of my seat. The machine 
starts sharply and turns upon its course. The wind seems 

17 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

suddenly to have dropped and I have been transferred to 
a downward-travelling lift, a tightness gripping my heart. 
I want to see where I have got to, but the sky appears 
beneath me and the earth in the sky. I have no sense of 
dizziness, strictly speaking, but I have lost all sense of 
direction. The silence is impressive; the pilot has shut 
down his throttle and I have closed my eyes. 

When I open them, only a few seconds later, I look 
over the fuselage and recognize the earth drawing rapidly 
nearer. Anxiety gives place again to enchantment. We 
are planing with silent engine, so that there is not the 
slightest vibration. We can see the earth once more in 
relief, things and creatures grow larger, the flying ground 
becomes more distinct. And now we have arrived ; a bump 
and we touch the earth, our journey at an end. It has 
taken us fifteen to twenty minutes to reach i,ooo metres, 
and scarcely five minutes to return. I experienced no sort 
of physiological phenomenon, except the sensation of fall- 
ing as in a lift at the beginning of the descent; no dizzi- 
ness, not even a whistling in the ears, neither fatigue, 
nor sleepiness, nor headache. 

There is nothing strange in this, for the height reached 
was not great, and the speed both in rising and in descend- 
ing was slow, say, two miles an hour in the first case and 
seven miles an hour in the second. 

It is by no means the same in flights at high alti- 
tudes, especially under conditions of high speed and rapid 
changes of pressure, as was seen during the war. The 
experiences both of pilots and observers must be taken 
into consideration. 

Physiological Phenomena. 

The Ascent. — In rising respiration becomes more 
rapid at about 2,000 metres and markedly so at 
4,500 metres. This is the most distressing pheno- 
menon. Shortness of breath is constant. At 5,000 
metres one observer became out of breath vv^ith 
faster and faster respiration on such small exertion 
as w^as demanded by the slightest movement. The 
attempt to change his seat even resulted in a diffi- 
culty in getting his breath. Inspiration especially is 
insufficient and the accessory muscles are called into 
action. 

18 



Tnr 0f'7r^ utr,v 

THE ASCENT 

Palpitation and a rapid pulse are noticed above 
2,000 metres. (In Lieut. D. a pulse-rate of lOO as 
compared with 80 at the time of departure.) 

Congestion of the facial capillaries takes place 
at about 4,000 metres. Formerly this phenomenon 
was observed at from 1,500 to 2,000 metres, for 
in the early days the precautions taken against cold 
were not sufficient. To-day the airman is much 
better protected; he is sheltered, warmly clad, even 
artificially heated. 

Anorexia, nausea, and even vomiting, occurred 
frequently amongst certain airmen who were 
examined by Ferry: a sensation of sea-sickness was 
noticed particularly in the eddies of warm air which 
press upwards upon the machine, or the eddies of 
cold air which draw it towards the earth. 

In addition to those whom we have treated for 
frequent and persistent vomiting occurring in the 
course of each flight and after returning to earth, a 
certain number have told us that they sometimes 
experience a true sea-sickness with distressing nausea 
when their speed in mounting was greater than 
usual, or their machine was tossed about to an 
unusual extent.^ 

A sensation of dryness of the mouth makes its 
appearance at about 1,500 metres. 

Desire to micturate is occasionally so strong that 
some airmen carry a urinal. 

Hearing. — One of the commonest sensations is 
that of fullness in the ears — the sensation of a cork 
placed in the auditory meatus. There results from 
it a certain degree of deafness, especially above 
2,000 metres. 

1 J. G. Ferry : " Le Syndrome mal des aviateurs," Th^se 
de Nancy, 1917, p. 47. 

19 



OL>li 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

Buzzings in the ears are also a common pheno- 
menon appearing under 2,000 metres if the ascent 
is made too fast. They often occur as clickings 
which sound like "rapid firing" (Ferry), and are 
not affected by the movements of deglutition. 

There is never any dizziness. Thus Lieut. B., a 
pilot who experienced dizziness on a doorway 20 
metres from the earth, was able to get out of his 
seat 3,000 metres in the air, stand upright on the 
landing carriage, and focus his camera without the 
slightest discomfort. 

Sight. — Disturbances of vision occur for the most 
part as psychic phenomena. The power of estimat- 
ing distances or the speed of another aeroplane is 
a faculty which must be educated. Novices some- 
times fail to see a German aeroplane passing at 
their side on account of the speed at which it passes. 
But physical fatigue also affects the sight : the 
reflection of sunlight from the clouds is very hard 
to endure. It is the airman's aim to keep the sun 
as much as possible on his left and behind him. 

The Sense of Direction. — It is chiefly in horizontal 
flight at altitudes of about 1,000 metres that young 
iiirmen develop their skill and muscular endurance. 
The sense of equilibrium is one of the most difficult 
to acquire. In a fog the most skilful airman com- 
pletely loses his idea of the horizontal : he has no 
longer any starting-off point. 

In the course of a voyage in the mist, writes the late 
Dr. Emile Raymond, 1 I was a whole hour without seeing 
either earth or sky, and therefore without any line of the 
horizon. 

In such a case the pilot easily loses his sense of the 
horizontal, particularly in the lateral direction; he does 
not notice that one wing is high and the other low, par- 

1 Bulletin Midical, November 11, 191 1. 
20 



THE ASCENT 

ticularly if he is so jolted as not to know which way he 
is sitting on his seat. 

I observed that the earth was nearer on my right and 
therefore that the right wing was lower, that the earth 
was further off on my left, the left wing therefore being 
higher. In order to right my machine I had to carry my 
joy-stick to the left. The fear of a mistake, which would 
have been disastrous, caused me to work out this argument 
twice over before carrying out the necessary movements. 

Every airman has had the same experience; after 
a passage through cloud or fog they often discover 
that one plane is lower, or that they are pointing 
dov^nwards or upwards, without ever being aware 
of the change in direction. Bernard recalls how 
Graeme Anderson went up in an aeroplane with his 
eyes bandaged intending to describe the move- 
ments of his machine to the pilot by telephone. At 
first his description was accurate, but after a time 
his conception of the aeroplane's movements and of 
his position in space lost their exactness. 

These facts tend to prove that our conception of 
equilibrium is to a large extent a function of the 
sense of sight. I (Cruchet) had an opportunity of 
discussing this question with Colonel Leclere, who 
had also been strucic with the loss of his sense of 
direction when flying through clouds. It appears 
tTiat this sense is gained by a prolonged education 
of the machinery of hearing. When we close our 
eyes in a motor-car or in a train, we have to be 
very careful if we are not to be deceived about the 
gradient of our path, either when we are going 
uphill or downhill, and the same thing applies also 
to our sense of transverse slope. Much more is 
this the case in an aeroplane when the starting-point 
of the earth's surface is wanting. 

Headache. — A temporal headache is experienced 
at a height above 2,000 metres, and more constantly 



21 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

above 3,000 metres. Above 4,000 or 5,000 metres 
the headache becomes very painful. At 5,200 
metres B. suffered so severely that he was obliged 
to descend : it is true that he had remained at 
this height for more than an hour. On two other 
occasions, after being for more than five hours at 
a height of over 4,000 metres, the unbearable pain 
compelled him to come down again. 

Movement. — Beyond 3,000 metres movements 
become quick, jerky and nervous; reflexes are 
sharper and the reactions produce movements of 
greater amplitude. Movement becomes more diffi- 
cult and requires greater effort, and a longer time 
is necessary for the achievement of the same result. 
Signals as transmitted by the Morse code are given 
out more slowly in proportion as the distance above 
3,000 metres is increased. 

Slowness of Ideation. — A half-torpor, a sleepy 
contentment creeps over the airman. He feels it 
difficult to concentrate his attention. His visual 
intelligence leaves much to be desired. Familiar 
objects within reach of his hand appear blurred. 
He looks for a compass or the barometer and can 
no longer find them; the revolution counter appears 
to be multiplied. A pilot with eighteen months' 
experience, flying at a height of 4,500 metres, saw 
seven or eight of these counters instead of a single 
one, and was obliged to put his hand on it in order 
to see it clearly. " This is really it," he said, as 
he touched it. He saw two or three oil gauges, 
the map fluttered in its case, the latter grew to a 
thing of immoderate dimensions. He dropped 500 
metres and all these phenomena disappeared. 

In proportion as one rises, gesture requires more 
energy, more time and greater effort. A simple 



22 



THE ASCENT 

sum which can be calculated on the earth in two 
minutes requires twice that time at 5,000 metres. 
To rise to 6,000 metres and come down to 2,000 
metres, to rise again to 4,000 metres, is exhausting. 
To remain three hours in the air has almost the 
same effect.^ 

The same anonymous author speaks of the sudden 
discomfort which is experienced by the most expert 
of pilots during the course of flight: "I do not 
know what was the matter with me. I felt myself 
growing weak." There is a tendency to believe 
that these sensations are connected with dizziness 
and disturbances of the ear, but this has by no 
means been proved to be the case. 

An Italian airman, Captain Ruffo, who has been 
through many flights at high altitudes, says that at 
6,000 metres he experienced a heaviness of the head, 
a sleepiness, a mental and physical torpor. This 
condition is very prejudicial to one's chances in air- 
fighting, for the combatant has need of all his 
agility of movement and quickness of thought. 

Another pilot at 5,200 metres felt his hands and 
his feet becoming numbed, their sensibility blunted, 
and the delicacy of touch considerably diminished, 
although he was not cold. When he withdrew his 
fur gloves, being once more on land, his hands were 
still livid, like the hands of a corpse, and all objects 
had an abnormal sense of roughness to the touch; 
the right leg was still heavy and paralysed. These 
phenomena persisted until the next day. 

Lumbago. — Lumbago is found chiefly among 
beginners and is to be explained by the fact that the 
lumbar muscles are required to do most of the work, 

1 U Illustration^ July 6, 191 8, pp. 6 and 9. 
23 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

since these correct the tendency of the head and 
shoulders to set themselves at right angles to the 
horizontal plane of the machine. 

The Descenti — In the descent emotional anxiety 
is experienced by novices and trained pilots who are 
suffering from fatigue. The moment when the 
throttle is closed must always be an impressive one. 
If the descent is made at a normal speed, say three 
to four minutes for a thousand metres, i.e., lo to 
12 m.p.h., nothing is noticed save some buzzings 
in the ears with a sensation of fullness of the 
ears which can be dispelled or diminished by degluti- 
tion. Occasionally when coming down in a close 
spiral those who are not accustomed to this method 
experience an unpleasant faintness of short dura- 
tion. On one occasion this occurred twice in the 
same descent (Ferry). 

But should the descent be swift, the phenomena 
already remarked upon are accentuated : hearing is 
greatly affected and becomes indistinct ; buzzings are 
increasing and auricular pain becomes intolerable. 
** The ears are forced open so that one might put 
one's fist in them,** so one observer has said; "it 
is as though a speculum were being forced into the 
passage and this were being torn to pieces*'; it is 
a sensation of '' scratching with a knife which stabs 
to the depth of the ear"; it is "a sharp pricking 
with a thousand sharp needles "; a " shrill unbear- 
able whistling like the whistHng of a steam 
engine " is heard. Even repeated deglutition 
scarcely affects this sensation. 

In rapid descent the sense of distance is lost 
temporarily and the altmetre at this time gives no 
exact information. Thus airmen are recommended 
to make a tour round the aerodrome before landing 



24 



THE DESCENT 

in order the better to estimate their distance from 
the earth. This is what they call " getting to the 
earth into one^s eye '' (A. Castex). 

At the same time a painful constraint, sometimes 
passing into a veritable sensation of burning, though 
not always very marked, affects the region of the 
heart. Palpitation appears and the tachycardia is 
increased. Respiration also is interfered with, 
especially inspiration, on account of the speed of 
the descent. Blood rushes to the face which be- 
comes red and congested. Headache is more severe 
in proportion as the speed increases. 

Finally, there is the tendency towards sleep with 
a relatively frequent state of syncope. This happens 
especially with young airmen who go in for acro- 
batic performances and with experienced pilots who 
are tired out by overlong flights. 

One of the airmen whom I have examined was 
seized at about 3,000 metres on two occasions with 
a sensation of torpor and weakness during his 
descent; he lost consciousness for the space of 
about one minute, and meanwhile his machine set 
itself in a spin. Fortunately he awoke in time to 
land safely with his passenger. 

These phenomena, and particularly the last, are 
reported by all who have inquired into the cause of 
air accidents since the war. 

In the descent, writes Castex, airmen are especially 
disturbed by the rapid transit from one altitude to another. 
One of them has told me that at least an hour is necessary 
in order to come down from 3,000 metres without experi- 
encing any discomfort. As they get nearer to the earth 
it appears that there are prickings in the ears, a sensation 
of moving liquid within them and of buzzings with head- 
ache. All these disturbances disappear when the airman 
lands and become considerably more serious if the machine 
dives, that is to say, during a sudden descent. They ex- 

25 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

perience under these circumstances a stupor which greatly 
hinders their control of the machine (G^zes).^ 

Panter is convinced that a large proportion of 
unexplained accidents are due to " loss of conscious- 
ness " of the pilot. He quotes four cases at least 
in which consciousness was lost in the air.^ Ander- 
son, examining at the same time the cause of fifty- 
eight accidents which occurred in the course of five 
thousand flights, ascribes four to cerebral fatigue, 
stupor or lethargy. If such accidents are rare in 
flying schools where the descent is usually made at 
a reasonable speed, it is by no means the same in 
the course of air-fights when it is sometimes of 
necessity faster than one would wish.^ 

Lieut. B., who was obliged to drop direct from 
1,200 metres to the earth as the result of an accident 
(his machine was on fire), occupied one minute only 
in doing so, a vertical speed of 56 m.p.h. On an- 
other occasion, in order to avoid a Gerrnan attack, 
he dropped full speed ahead from 4,200 to 3,000 
metres in twenty seconds, or at 124J m.p.h. He is 
very clear in his description of the above-mentioned 
phenomena during these experiences. 

Another officer was wont to amuse himself by 
dropping in a spin from 2,000 metres which enabled 
him to pass through 1,000 metres in half a minute, 
that is to say, at 74 m.p.h. One day the phenomena 
above mentioned were so marked — particularly the 
sensation of cardiac constriction — that he became 
thenceforth more prudent. 

^ A. Castex : " Troubles auriculaires chez les aviateurs 
militaires," Archives de med. et de -pharm. militaires, 
July I, 1918, pp. 1^-1^. 

2 Panter, Journal of the Royal Naval Medical Service, 
January, 1918. 

3 H. Graeme, British Medical Journal, January, 191 8. 

26 



THE DESCENT 

The same observations result from the experiments 
of Messrs. Marchoux and Nepper who were enclosed 
in a Paul Bert bell-jar at the Sorbonne. Although 
those who showed reactions experienced head- 
ache and pain in the ears during the progressive 
decompression to a point corresponding -with the 
pressure normally found at 6,000 metres, it was the 
recompression (descent) which was least successfully 
borne by all, and particularly the last 1,000 metres. 
Frequently it was necessary to interrupt the recom- 
pression to enable them to recover from the distress- 
ing symptoms to which they were subject. Head- 
ache, auricular pain, neuralgia, sometimes dizziness 
and even nausea, also threatened syncope, compelled 
the authors to decrease the speed of recompression 
to 12 m.p.h. during the last 1,500 or 2,000 metres.^ 

To recapitulate, all airmen experience phenomena 
during rapid descent, especially in diving with the 
throttle open at a speed of no m.p.h. These 
phenomena are increased in proportion to the height 
from which the descent is made. For this reason 
airmen usually fall by successive stages so as to 
diminish distressing symptoms and in this way are 
able to reach the earth without suffering any serious 
harm. 

There is still another phenomenon of which we 
must take account; it is that of "the attraction of 
the earth,'' which Garros in particular pointed out 
to us in January, 1914, and which is fairly common- 
place in the experience of airmen who are accus- 
tomed to remain a certain space of time in the air. 
When they begin lo descend they feel themselves 
seized with an " irrational," imperious impulse to 

1 Marchoux and Nepper, SociHe de Biologie, June 21, 
1Q19, pp. 668-673. 

27 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

return with the greatest possible speed to the earth. 
A great amount of self-control is required to prevent 
them from coming down faster than is actually neces- 
sary. Often when they are a little tired they have 
not the strength of will to overcome this impulse, 
although their reason tells them that to yield is both 
useless and dangerous. 

The Landing. — When the airman has safely landed 
there is often observed a fibrillary tremor of the 
extremities; the pulse is quickened, there is hyper- 
tension, especially of the minimum pressure, diminu- 
tion in the amplitude of oscillation, congestion of 
the face, all to a greater or lesser extent. Buzzings 
in the ears and deafness persist, but the auricular 
pain decreases in intensity. There is no nystagmus. 
Sometimes there is a heaviness in jumping down 
from the machine, staggering gait is seen after long 
raids. The headache continues. There is a strong 
desire to micturate, sleepiness and exaggerated 
sensibility of the nerves. 

In the case of experienced airmen who have been 
a long time in the air, or who have made a too rapid 
descent, the call to sleep is urgent. Most of them 
realize that they are very irritable and highly strung 
during the descent and the hours which immediately 
follow it. Even the most stolid and amiable 
amongst them admit themselves to be bad-tempered 
on such occasions. 

Sometimes they go to sleep on the first bench 
which comes in their way, and it is a deep sleep 
which may last for an hour or more. It is a com- 
mon-place of the aerodromes for pupils who have 
been up to perhaps 2,000 metres for not more than 
half an hour as observers, hastily to seek their beds, 
where they swiftly fall asleep. 

28 



THE LANDING 

These phenomena are accentuated by rapid 
descent, nose-dives, or spins. The headache is 
persistent, as are also the buzzings and the deafness ; 
fatigue is extreme, drowsiness overwhelming. These 
troubles diminish within twelve to twenty-four hours, 
But they have a tendency to reappear with greater 
readiness if the airman does not take sufficient rest. 

The flying men do not seek amusement when they come 
back to port. They sleep the sleep of the exhausted. 
Nothing can waken them. There will be a saying after 
the war : " To sleep like an airman. "i 

Dh. . . , one of our aces, in the spring of 1918, 
with 1,500 hours' flight to his credit and a record of 
seven successful duels, described to us as follows 
the dizziness and sleepiness which he experienced 
after shooting down an enemy aeroplane at 6,000 
metres; he followed it in its descent. On landing, 
as he came out of his machine he staggered as if 
drunk and was obliged to stand still. Staggering is 
a common experience to him after sudden descent. 
Since that time he has had dizziness which formerly 
never troubled him. Often drowsiness assails him 
while he is flying; sometimes he falls asleep in his 
machine. It happened recently that he passed 
unwittingly over our lines on his return. He tells 
us that he has never experienced either palpitations 
or dyspnoea on exertion. But now the least effort 
makes him feel extremely tired. 

It is our opinion that the craving for alcohol with 
which airmen have been so much reproached is 
really due to the necessity of fighting against the 
invasion of this lethargy, which so often maintains 
its hold after the flight is over. Furthermore, the 

1 U Illustration^ July 6, 1918. 

29 



THE PHYSIOLOGY OF FLYING SINCE THE WAR 

persistent thirst which is met with after long, 
repeated and exhausting raids, may also have some- 
thing to do with this. 

Contrary to the general belief, the sex instinct 
tends to decrease in force in proportion as the hours 
of flight are prolonged. This has been confided to 
us by many airmen. Some have even ass«erted that 
they were subject to a transitory impotence.^ 

A loss of muscular power has also been described 
after flight, both by pilot, observer and passen- 
gers. Also a decrease of cutaneous sensibility, 
exaggeration of the tendon reflexes (Juarros),^ and 
a sHght hyperglycsemia (o'i5 to o*i8 instead of 
0*09 to 0'i2).^ But these facts, which are encoun- 
tered in most people who have been recently 
occupied with physical exercises, do not appear to 
offer any peculiar interest by their appearance in 
airmen. The hyperglobulia of high altitudes which 
was discovered by Viault (of Bordeaux) was also 
observed by GemelH in airmen in the year 1917. 

Amongst the phenomena observed on landing, the 
most important in our opinion is that of arterial 
hypertension. We have shown how ever since 1910 
our attention has been particularly directed towards 
it. For this reason it is of great importance that 
we should closely examine this question into which 
undeniable errors have crept through the wrong 
interpretation of many factors. 

1 This impotence has even been observed as a sequel 
to repeated diving-bell experiments, during which the 
pressure had been lowered to that which corresponds to 
an altitude of from 5.000 to 7,000 metres. In one case it 
lasted for three months. 

2 Societi de Biologie de Paris, June 21, 1919, p. 692. 

3 G. Maranon : SocieU de Biologie, June 14, 1919, 
p. 631. 

30 



ARTERIAL HYPERTENSION 



CHAPTER III. 

The Etiology of Air Sickness, 

Arterial Hypertension. — Since 1910, when we first 
undertook our researches, we have insisted upon 
the importance of those changes of arterial pressure 
which are noticed in airmen during the course of 
flight. We have remarked that the minimal tension 
is constantly increased after descent from high 
altitudes; the maximum tension also shows an in- 
crease, but the latter is of scarcely any significance 
in comparison with that of the minimal. The maxi- 
mum pressure indeed was sHghtly lowered in course 
of flight at low altitude. 

It was then the hypertension of the minimal 
pressure which we found particularly striking. We 
took care that our experiments were only carried 
out upon "athletes in perfect training," for, as 
we have pointed out, this hypertension may be 
diminished or even converted to hypotension in 
the case of those who are fatigued or who are 
suffering from cardiac insufiiciency. 

Diagram i, which appeared in the Salon of 
aeronautics at Paris in 191 2, illustrates this point 
extremely well. To it we have simply added over 
the letters M and P some observations made by 
Crouzon which were pubhshed about the same 
time. Though they record Mx. pressure only, they 
strictly confirm our own observations (fig. i). 

Fatigue modifies considerably the vaso-motor 

31 



THE ETIOLOGY OF AIR SICKNESS 

Observations made ui>on airmen (b) before and 
(a) after flight. 



^ 


Ot? 




of 


c 


^9 


^ 


21 


^^ 


20 


^ 


19 


120 


18 


NO 


J7 


100 


16 


90 


15 


eo 


14 


70 


13 


60 


12 




II 




to 




9 




8 




7 




6 




5 




4 




3 




2 

1 



/it moderste a/t/'tudes 
(/,200to 2,500 metres) 



d 



M N 



At /OiA^ 

a/titudes /SO 
to 400 metres 



a 6 



M P 



By C 



la 

^^ o 
6 - ^ 



b 



Br 



«— Pulse rate, ^^m- Pulse rate (b) assurrted 
^ Arter/af pressure in Crn of Hy (M/htms) 
CD *i »» " " (/Vfaxima) 

Fig. I. 

This diagram shows clearly {«) the increase of Mn. 
pressure on landing. These figures were taken in Sep- 
tember, iQio, at Bordeaux on the following well-known 
airmen : Legagneux (L), Leon Morane (M and N), Naval 
Lieut. Byasson (By), Lieut. Cammermann (C), Juilleret 
(J), Br6gi (Br). In the case of the latter only Mn. pres- 
sure is decreased as a result of an attack of faintness. 

The figures for Mahieu (M) and Paumier (P), recorded 
in March, 1912, by Dr. Crouzon, are only concerned with 
the Mx. pressure, which was markedly increased. 



32 



ARTERIAL HYPERTENSION 

reactions, the mechanical conditions of the circu- 
lation and the contracting power of the myocar- 
dium. The conclusions of certain authors are 
open to criticism in that normal subjects have been 
compared with fatigued and the Mx. pressure only 
has been considered, the value of the Mn. pressure 
being omitted from the observation. It is inter- 
esting to take up again the study of this hyper- 
tension considered in the Hght of literature which 
has appeared since the war. 

Since 1913 we have had the assistance of M. 
Ferry, a resident physician of Nancy Hospital, at 
that time auxiliary physician to the aviation centre 
of Epinal. At our request he took up our re- 
search, confirmed our observations, and was able 
to measure changes of pressure during the course 
of flight so as to have a complete record. M. Ferry 
set to work and we give below the extremely in- 
teresting results which he obtained at that time 
and which he has been able to confirm during the 
war.^ 

In order that these results may be compared with 
our own diagrams, we have tabulated them in the 
same v/ay. We thus obtain fig. 2. 

In comparing this figure with our own results 
{fig. i), we observe that the latter are amply con- 
firmed. We find that the changes in Mx. pressure 
are of little importance and that at low altitudes 
this even tends to be lowered. 

But the hypertension of the Mn. pressure which 
alone indicates the true state of the heart, is of 

^ J. G. Ferry : " Le syndrome mal des aviateurs," 
Presse medicale, February 14, igi6, pp. 65-67. See also 
another article by the same author on the same subject, 
These Nancy, J. B. Bailliere et Fils, 1917. 

33 



THE ETIOLOGY OF AIR SICKNESS 

far greater importance. In this respect Ferry's 
observations confirm our own. 

Observations made iii>on F. (b) before, (d) during and 
(a) after flight. 



I 

i. 

120 
110 
100 
90 
80 
70 
60 



Cm 
cf 

21 
20 
19 
18 
17 
16 
15 
14 
13 
• 2 
II 
10 
9 
8 
7 
6 
5 
4 
3 
2 
I 



At mocferate 
^/t/'tuafes f2,000 
to 2,500 metres) 




FVn F4 f.7 



At /o^v 
a/tttudes f600 
to f,250 metres) 



^ t 



m 



bd 



m. 



(k 'id iii 

F.3 F.IU FVI 



•— Pu/se r^t& 

WUkArter/'a/ pressure in Cm of /-(^ (A7/n//:;»^ 

Fig. 2. 

This diagram shows the pressure changes Mx. and Mn. 
not only before [b) and after flight on landing (^), but 
also during flight {d). They are results obtained by pilot 
Dr. Ferry, who published them in igi6, and closely con- 
firm those shown in fig. i as far as hypertension in Mn. 
pressure is concerned. 



34 



FATIGUE 

If we compare the pressure before flight (b) with 
that after (a), the hypertension is clearly shown. 
If we compare the pressure during flight (d) with 
the pressure on landing (a), hypertension is still 
more marked. 

This hypertension during rapid descent is in our 
opinion of the greatest importance. 

Our diagram of Br (fainting attack) is strictly 
comparable to that of Ferry, who had two fainting 
attacks in the course of a rapid spiral descent. 
In this case there is hypotension both of Mx. and 
Mn. Mx. in the case of Ferry shows a tendency 
to recover if the point (d) be compared with point 
(a). But actually at (a) it shows a decrease in 
comparison with (b). 

We therefore conclude that arterial hypertension, 
particularly of the Mn. pressure, during rapid 
descent and following upon a hypotension of the 
same pressure during the ascent, is a normal 
reaction in the airman. 

We must now discuss this factor in relation to 
others, amongst which the most important are 
fatigue, cold, mental strain, emotion and speed. 

Fatigue. — There are those who believe that the 
factor of fatigue, mental as well as physical, is of 
fundamental importance. They liken disturbances 
occurring in airmen to those experienced by 
athletes in the course of various tests of endurance, 
such as horse-riding, motor-racing, cycling and 
flat-racing. 

At times when fighting was severe, pilots were seen 
returning in rough weather to the landing ground, having 
finished their work, and a few seconds afterwards they 
appeared incapable of the effort necessary to land their 
machines, which were broken in the shock of contact with 

35 



THE .ETIOLOGY OF AIR SICKNESS 

the earth. Air •sickness has nothing to do with these cases. 
It is simply a question of many being tired out by too hard 
work. 1 

Doubtless fatigue makes it possible for disturb- 
ances to appear at much lower altitudes than they 
do in climbing or balloon ascents; it cannot, how- 
ever, explain the arterial hypertension which has 
been observed; in fact experiments of this kind 
carried out on athletes result in an arterial hypo- 
tension at the first sign of fatigue. This fact, which 
controverts the statements attributed to Bleriot and 
Dr. Bregi, has been demonstrated by Pachon and 
is clearly shown in the case of footballers, as we 
found during the winter 1910-1911 in the course of 
some hitherto unpublished researches. In the case 
of airmen hypertension at least of the minima has 
been our invariable observation. 

Let us in the first place determine precisely by 
what means we are able to recognize fatigue.^ 

Criteria of Fitness. — It is less simple than one 
might think to estimate fatigue. Many people who 
complain of being tired are less exhausted than 
they say, and on the other hand, there are others 
who in reality are more fatigued than they think. 
In fact fatigue is largely a subjective sensation — 
a sensation which we try to express in phrases 
which are neither precise nor capable of com- 
parison. The same thing is true of fatigue as of 

^ L' Illustration J loc. cit. The author is quite right in 
saying that air-sickness and fatigue are not the sarne 
thing. But how can he prove that fatigue alone is in 
question in the cases which he reports? Fatigue by itself 
coming on a few seconds before landing, is a far less 
satisfactory explanation of the fall than is a sudden 
physiological disturbance which carries away the reserve 
strength, the last remaining resource of the airman. 

2 See the Petite Gironde, May 19, 1914. 

36 



FATIGUE 

pain, that it is a quality which varies with each 
individual, and that so long as we confine our 
attention to the information provided by the sub- 
ject himself, we cannot measure doses of fatigue 
in mathematical terms. One will answer us that he 
is completely knocked up, when a careful physio- 
logical examination shows that he is very far from 
collapse. Another — and this happens daily among 
many of our modem athletes — will pretend that a 
hard game of football and a long cycle ride leave 
him at the end as fresh as he was at the beginning, 
whereas his heart-sounds, his pulse-rate and the 
record of his arterial pressure enable us to diagnose 
indisputable fatigue. 

It is therefore necessary to resort to scientific 
methods in which the personal element is not in- 
volved. Thus we have turned successively to 
examinations of the cardiac muscle and its pulsa- 
tions, and to the minute study of the results of 
urine analysis. But the information derived from 
these studies was not sufficient to enable us to 
assign to each individual under consideration the 
quantity of work which he might accomplish 
without overtiring himself. 

In his 1910 memoir Pachon solved this difficult 
problem in the following way.^ It is known, he 
says, that the distress of an organism in bad train- 
ing is due to reactions associated with the heart and 
that it is in this quarter that pathological results 
are likely to follow an ill-considered strain. The 
question then is how to track the origin of this 

^ Societe de Biologie, May, 1910. See also : Antoine 
L^ger, " Contribution a I'etude du critere oscillometrique 
consid^re comme critere d'entrainement en education 
physique," These de Bordeaux. March 27, IQ14. 

37 



THE ETIOLOGY OF AIR SICKNESS 

reaction of cardiac distress. With this end in view 
our eminent colleague selected two subjects, the 
one in training for a life of physical activity, the 
other untrained and accustomed to a sedentary 
existence. He made them go through the same 
exercise for three minutes and observed in the case 



1 


Minutes . 1 


/^ 


5 


10 


15 


20 


25 


30 


35 


40 


45 


50 


55 


18 
17 

16 
15 
14 
13 
12 
II 
10 
9 








Wi. 


>rk 


pis 


tea 


•J. 














J 


/ 








\ 














/ 












\ 


A 






m: 


fj 












1 






\ 


\. 




■w 












1 










vj 


































> 


/ 


\esx 






1 


p 












i 












1^ 


y 


/" 








\ 


^ 


..... 






•- 


^ 


^ 
















V 


•*» 


M 


y 





















Fig. 3. 

Gscillometric test showing the adaptation of an 
individual to work (after Pachon). 

of each by means of the oscillometer what were 
the values (maxima and minima) of arterial pres- 
sure before and after the experiment. He found 
that in the untrained individual these values were 
immediately diminished, whilst in the trained sub- 
ject not only did they not fall, but were even 
slightly increased. This is what he called the 



38 



FATIGUE 

oscillometric test which enables us to estimate the 
power of adaptation of any individual to a given 
exercise. 

This may be seen in the graph shown in fig. 3. 
The figures were obtained from a subject in train- 
ing well adapted to the work which he carried 
through; and the pressures, especially the maxima, 
are seen to rise under the influence of muscular 
exertion. This is what Pachon calls the zvorking 
value, which expresses the work done by the heart 
in response to the demands made upon it by the 
caUing into action of large groups of muscles. For 
some time the pressures remain at this same height, 
constituting the work plateau, that is to say, the 
condition of adaptation to exercise of the individual. 
In the example illustrated by this figure, the plateau 
is maintained throughout the duration of muscular 
effort, thereby proving the absence of fatigue and 
the perfect training of the subject whose pressure 
values return almost to their previous position. 

Let us now see what happens in the untrained 
individual when fatigue makes itself felt. The 
same result will follow when he is overtrained or 
when he has continued his exertions beyond the 
limits of his physiological endurance (see fig. 4). 

Here, as in the previous case, the pressures are 
seen to rise in the first instance up to the level 
of the work plateau, but in this case the plateau 
maintains its level for a short time only. After an 
interval of about five minutes (this interval naturally 
varies in different cases) a fall of pressure — chiefly 
in the maxima^ — indicates tlie faiHng of a heart 
inadapted to exertion. It is this diminution of 
arterial pressure which Prof. Pachon has described 
by the expressive phrase of danger signal. It is 

39 



THE ETIOLOGY OF AIR SICKNESS 

the indication for stopping exercise, for it immedi- 
ately precedes the moment when fatigue is shown 
in an objective manner, whether or not it is 
perceived subjectively. 

If in spite of this danger signal the individual 
persists in his exertions, he overworks his heart 



1 


Minutes 

.... - A ..- 


r 


5 


10 


15 


20 


25 


30 


35 


-so 


45 


50 


55 


17 
16 
15 
14 
13 
12 
11 
10 
9 
8 






)No> 


^f<P 


'stt 


'SU 




















r 






















J 






\ 
















^ 


^ 






\ 
















L 








\ 


























V 




A 








♦J 












s 


V 


r 








^ 


: 










V| 














1^ 


,©- 


- 






1 




A 


es 










«^ 


u 


■^ 


^ 








^^^ < 
















"*" 




"^r\ 



Fig. 4- 

Oscillometric test showing initial phase of temporary 
adaptation followed by failure of adaptation (from the 
Leger Thesis). 

and the pressure falls still lower. It may even fall 
so low that it will actually rise after the exercise 
is concluded. Under these conditions hypotension 
not only appears at the time of greatest strain, but 
it continues for a greater or less period during the 
subsequent rest. Thus it will be seen from the 



40 



FATIGUE 

graph in fig. 4 that twenty-five minutes after ceasing 
exercise the arterial pressure still remains abnormal. 

Let us now apply this oscillometric test of 
training, which consists in the systematic study of 
arterial pressure variations and the results of which 
can be expressed diagrammatically, and in the first 
place let us consider the results obtained from a 
series of Swedish exercises (fig. 5). 

The values expressed diagrammatically over the 
letter N are the same as those which are repre- 
sented graphically in fig. 3, and similarly the 
diagram P corresponds to the graph in fig. 4. N is 
trained. P is fatigued. 

The same results appear in the bicycle race. 

L shows adaptation throughout a race of 36 miles 
of good road, the Mx. pressure increasing with the 
effort necessary to cHmb two hills (d and d'). 

S, aged 23, shows failure of adaptation. Over 
20 miles of hilly road between Bordeaux and 
Libourne both Mx. and Mn. pressure show a 
tendency to fall. Even during a period of exertion 
they fall (at d) below the original pressure (b) and 
give way to a still greater extent after the race (a). 
At the same time the oscillations show a diminution 
of amplitude. 

The same results appear again in the exercise of 
carrying wood upstairs. (The subject of this experi- 
ment went up sixty-four steps in three stages.) 

L shows temporary adaptation, followed by loss 
of adaptation, the Mx. and Mn. pressures (at r) hav- 
ing fallen below their original value (at b). The 
oscillations are small. 

Strictly analogous were the results obtained from 
flat races (fig. 6). 

On May 12, 1912, the celebrated athlete Bouin, 

41 



THE ETIOLOGY OF AIR SICKNESS 



Observations made (b) before j (d, d') during^ (a) after and 
(r) at rest in the course of Swedish exercises, bicycle 
race and climbing stairs with a load of wood. 



Cm 





°4 

22 


1 


21 
20 
J9 


120 


18 


110 


17 


100 


16 


90 


15 


80 


14 


70 


J3 


60 


\Z 




II 




10 




9 




8 




7 




6 




5 




4- 




3 




Z 



Si/^e&f'sh exercises 




Cyc/e r/cfe 




C^rry/no 

wef'ffht 

upsts/'rs 



• — Pu/se rate 

W& Arterial pressure /'n Cm of Hg (/if in /ma) 

cm '^ M «' r» (May /ma) 

Fig. 5. (After Leger.) 

In Swedish exercises N is in perfect training since 
pressure Mx. and Mn. increase during exercise [d, d'), and 
return after exercise {at a and r) to their original value {b). 
P shows failure of adaptation, pressures at d' and a being 
below that of b. 

Bicycle race. — L shows adaptation, whilst S shows 
failure of adaptation. 

Climbing stairs with weight. — L shows temporary adapta- 
tion only. 

42 



Observations made (b) before, (d, d') during and (a, a') 
after a flat race and gyynnastic exercises. 



V) 

? 

1 

140 
130 
120 
110 
100 
30 
6 
70 
€0 




Cymnasttc exercise 




^ 


m' n\ 1 

r n 


a 
1 




■ -^ 






L1 L2 L3 


5 



Bon Li Lf 



« — Pulse rate 

ra Arterial pressure In Cm of Hg (Minima) 

O M '/ " >f (Maxima) 

Fig. 6. 

Flat race. — The failure of adaptation in this diagram 
betrays a very evident fatigue. Bo represents the cele- 
brated flat racer Bouin, whom we examined at Bordeaux 
on May 12, 1912. He was at that time engaged in a race 
over 5i miles with three competitors running in relays. 
It is worthy of remark that Bouin, who won the race in 
28' 37 4-5", is no more fatigued than his competitors. He 
is even less fatigued than Lafue (Lf). 

Gymnastic exercises. — Dr. Leger (Bordeaux Thesis, 
1914) shows adaptation to the strain in Li, since the pres- 
sures, particularly the Mn,, return after a to their value 
at b. Failure of adaptation is shown in L2 {d')., and is 
still more clearly manifest in L3 {d' and particularly a). 
It is also shown in S. 

43 



THE ETIOLOGY OF AIR SICKNESS 

racing at the Bordelais University Athletic Club, 
ran over 5 J miles against a team of three in relays. 
He ended a good first from a magnificent spurt 
against a fourth runner who had only the last lap 
to run against him. Each of the previous three 
runners were also beaten in succession. 

This diagram is the more remarkable in that it 
shows Bouin to be in the best condition at the 
finish, despite the effort which he had furnished. 
There is, nevertheless, a sHght diminution of pres- 
sure. 

The si n^iles (8*8 kil.) were covered in 28' 37 4-5'^ 
the last I mile in 61 seconds. Bouin was 23 J years, 
his competitors were as follows : Bonnafond, 38 
years; Lacombe, 2y years; Lafue, 22 years. 

Each of the last three runners show marked 
failure of adaptation. The heart volume was in- 
creased, the pulse compressible, the first heart sound 
prolonged. Undoubtedly the heart was fatigued in 
each of these cases. 

Again the same observations were made in gym- 
nastic exercises (fig. 6). 

L marched 660 yards au pas gyfnnastique^ one 
hour after the evening meal in cold, fine weather. 
The ground was level, except for the last 100 yards 
which was steeply incHned. The time taken was 
15 minutes. The first diagram shows adaptation. 
Oscillations 3 — 4 — 3. In the second case 3,500 yards 
were covered in 20 minutes — in two stages of 10 
minutes each. The limit of adaptation reached, 
oscillations are weaker: 2 — 3 — 2J. In the third case 
3,300 yards were stepped in 30 minutes — six stages 
of 5 minutes each. This case shows definite failure 

1 At the double with knees raised. 
44 



I uuh_K(Tri r./ifip,riOc 



FATIGUE 



of adaptation and even weaker oscillations : 
2— 2j— ij. 

S also shows failure of adaptation. He covered 
1, 800 yards in 10 minutes and then after 10 minutes 
of rest 330 yards farther. 

Similar obsei-vations were made on a Rugby 
football team. We made more than 100 observa- 
tions, nearly all during the season 1910-1911, when 
one of us (R. Cruchet) was a member of the Rugby 
Committee of the Bordelais University Athletic 
Club, and regularly observed the players. They 
were kept in perfect training up to the last match 
— which they won and with it the championship of 
France. That was the year of what was called the 
" Virgin Team,*' for they did not sustain a single 
defeat. 

We have selected for our diagrams the most 
characteristic results. 

In the first place we give examples of untrained 
individuals (fig. 7). 

(i) Referees. — H represents Hutchinson, the 
official referee, aged 40. His curve, taken on 
November 10, 1910, shows a complete absence of 
training. Williams is a celebrated English referee 
who came to Bordeaux for the famous game against 
the South Africans on January 11, 191 3. There is 
evident want of training in this case also, though 
it is less pronounced than in the former case. 

(2) Players. — An examination was held at the 
beginning of the football season (1910) when lack 
of training was obvious. The observations were 
made on Brachet (age 24), Canton (age 24), Laffitte 
(age 2y), Monier, Martin, Droz (age 29), Jameton 
(age 25). In the case of Martin the examination 



45 



vir.u or no HO 



THE ETIOLOGY OF AIR SICKNESS 

Observations made on footballers (b) before and (a) after 
a game. 



!30 
120 

no 

100 
90 
80 
70 
60 



'-f 


Referees 


Hg. 




24 


b 




23 






22 






21 






20 




b 




19 




1 r 




^8 








17 




a 


fa 


16 


i 






15 








14 








13 




i 




12 


1 






II 


^ 






10 


1 


, 




9 


1 


1 




6 


1 


1 1 


^ 


7 


j 


1 1 


1 


6 


1 


j j 


j 


5 


^ 


^ 1 


1 


4 




1 ! 


1 


3 




j 1 


1 


2 


j 


j 1 




1 


1 


II 


1 




1 


^ V 


V 



Players 



Captains 




11 



Bra C L Mo Ma Or 



t^ 



IVl 



• — Pu/se rate 

^M A rter/'a/ pressure m Cm of Mg (Mint ma) 

O '• " •' »' (Maxima) 

Fig. 7. 

This diagram shows considerable hypotension. Especi- 
ally interesting are the records of Monier (Mo), Laffitte 
(L), Martin (Ma), the well-known members of the Borde- 
lais University Club Team. H and W represent records 
taken from two referees. Leuvielle (L) and Millar (M), 
the captains in the game against the South Africans, held 
at Bordeaux on January ii, 1913, also show slight fatigue 
after the game : there is diminution of arterial pressure. 



46 



FATIGUE 

was made after a hard game and one of the first 
in which he had played. 

(3) Captains. — Leuvielle was the French captain 
and Millar captain of the South Africans in the 
match of January 11, 1913. Both players show 
slight hypotension. The game had been hardly 
contested and both were beginning to feel fatigued. 

Fig. 8 shows training in progress. Fig. 9 the 
team of the Bordeaux Club already referred to on 
the day (April 9, 191 1) on which they won the 
Championship of France. 

The same reactions were observ^ed in the course 
of swimming races (fig. 10). In the speed race the 
temperature of the water was 17° C. Pierre T. 
swam the 100 metres in i' 40". The increased 
pressure occurred only in the course of the effort 
or immediately after coming out of the water. 
One hour after the race the pressure had returned 
to normal. 

Four days later the same swimmer covered 
the same distance in i' 32". Immediately after 
the race the pressure had risen from 16 to 22. 
One hour afterwards it was 21, two hours after- 
wards 19, three hours afterwards 17, five hours 
afterwards it returned to normal. In this case 
adaptation is perfect. 

Lecam swam 400 metres on October 4, 1910. 
The temperature of the water was then 90 C. 
He covered the distance in 7' 29". The Mx. 
pressure rose from 18 to 23 during the race and 
returned to 18 four hours afterwards. Lecam 
states^ that at a temperature of 22 to 25° C. one 
can stand immersion for a considerable time. At 

^ Lecam : " De la natation au point de vue medical," 
(These de Bordeaux, July, igii). 

47 



THE AETIOLOGY OF AIR SICKNESS 



Observations made on the same footballers (b) before and 
(a) after a game_, showing the effect of training and 
overtraining. 



i 

120 
110 
100 
90 
80 
70 
60 



Cm. 
of 

18 
17 

16 
15 
14 

13 

12 

1 1 

10 

9 

8 

7 

6 

5 

4- 

'3 

2 

I 



/ // m hfghfy IV 

untrained in tnsining trained overtrained 




Bo I 



m 

II III CI JI III 



CD 



II ni Bey 

Pufse rate 

Arter/s/ pressure in 



Cm of/yy (^M/'nima) 
It /» (fy7aximQ) 



Fig. 8. 

Three members of the team reached the end of the 
season in good condition. One (Perrens) was overtrained. 
Observations were taken on the following dates : — 

Boyau Dec. 4, 1910 March 12, 1911 Apil 9, 1911 

De Beyssac Dec, 11, 1910 Jan. 14,1011 April 9, 1911 
Canton Dec. 4,1910 JFeb. 19,1911 April 9, 1911 

(Boyau is the celebrated airman who disappeared in the 
course of the war. Conilh de Beyssac, also a Vv'ell-known 
sportsman, was killed on his tank in action in 1918.) 



48 



FATIGUE 



- -^ 

Observations made on footballers (b) before and (a) after 
a Rugby Football Chanvpionshi^ Final. The results 
show the fine condition of the 'players. 



_^ 

120 
MO 
100 
80 
60 
70 
60 



Cm. 
of 

16 
17 
16 
15 
14 
13 
12 
t I 
(0 
9 

e 

7 
6 
5 
4 
3 
2 
I 



ffsyers frt perfect training 




bj^ 



6d 

r 



^, 



f 



6A 




L Mo A ec> La Ca Bo F.R Br D I S P« Ma A.R 

e— Fu/se rate 

{^ Arterial pressure in C/n of^^ (Minima) ^ 



Fig. q. 

Leuvielle (Capt.), Monie, Anouilh, de Beyssac,* Laffitte^ 
Canton (Rene), Boyau,* Fernand Perrens,* Bruneau, 
Dufau,* Ihingou^,* Strohl, Pascarel, Martin. 

Andr^ Perrens alone is overtrained. 

(Players marked * lost their lives during the war.) 
49 



THE ETIOLOGY OF AIR SICKNESS 



Observations made (b) before (d) during and (a, a') after 
swimming races and a shower bath taken by a foot- 
baller. 



1 


of 
23 


22 
21 
20 


130 


19 


lao 


18 


f»o 


17 


ioo 


16 


90 


15 


eo 


14 


70 


13 


60 


12 




tl 




10 




9 




e 




7 




6 




S 




4 




3 




2 




1 



Deep i/yater r&ce 



Sfieecf race 



a b 



k 



Shower 
bath 



B N- 8a R Bx 

•— Fu/se rate r> ^ /^ • 

WH Arterial pressure in Cm or ng. (M/n/ma) 
\ — \ // »* » " (Maxima) 

Fig. id. 

In the deep water race all the swimmers show a slight 
diminution of pressure after {a) the race. This is more 
or less marked in the case of the Mx. (excepting Ba), as 
well as of the Mn. There is failure of adaptation and 
fatigue. 

In the speed race T and L show perfect adaptation. 

After the shower bath Mo shows marked failure of 
adaptation. It is true that the bath was taken after a 
hard game of football. 

50 



FATIGUE 

18° C. cyanosis, coldness of the extremities and 
chattering of the teeth come on after two hours. 

Deep-water Race. — The swimmers had taken 
part in the races at Bordeaux on June 30, 1912. 
The total distance from Lormont to Bordeaux, 
about three miles, was covered by Bonzom in 
37' 5^ 3"5"- All the swimmers showed some failure 
of adaptation, being more or less fatigued by their 
exertions. But they were very much fresher than 
the flat racers. 

The temperature of the water has to be taken 
into account, for it also plays its part. In the 
case of a shower bath, taken by a subject already 
suffering from fatigue, it causes a fresh diminution 
of Mx. and Mn. pressure. This diminution was 
probably secondary to a temporary hypertension 
which was caused by the shower itself. The 
cardiac musculature gives way in proportion as it 
is fatigued, the stimulation having only a temporary 
effect. 

To recapitulate, all work, all output of energy is 
accompanied by changes in the circulation. When 
the work done does not exceed the limits of physio- 
logical resistance — either natural or acquired by 
training — the observed variations of arterial pres- 
sure follow a rhythm which may be considered as 
the criterion of the patient's adaptation to that 
work. 

We can follow decadence of this rhythm in 
various forms of sport with such regularity thai: 
Pachon has made use of it as a test of training. 
Avjiation is an exception to the rule of ordinary 
sports. The arterial pressure of the airman in the 
course of his flight does not vary in the same way 
as in other athletes. It is particularly in the Mn. 

51 



THE ETIOLOGY OF AIR SICKNESS 

pressure that the training test of the airman departs 
from the ordinary rules established by experiments 
in athletics. 

The Mn. pressure, which decreases during the 
ascent in inverse ratio to the altitude, rises again 
during the descent; its rise is more marked as the 
speed of the descent becomes more rapid. This 
hypertension of Mn. pressure is a phenomenon 
quite peculiar to aviation. It is in contradiction 
to the phenomena v^hich we observe in the case of 
athletes engaged in other forms of sport. 

Most remarkable is the fact that it may even 
coincide with indisputable fatigue in the airman, a 
condition which should result, according to the 
physiological laws which we have just enunciated, 
in a marked hypotension. The hypotension, and 
this is one of its essential characteristics, is of 
short duration only. At the end of a few hours 
pressure returns to the normal. It is not rare for 
the normal tension itself to become a persistent 
hypotension during rest in proportion as the airman 
is fatigued. 

It therefore appears that the hypertension of Mn. 
pressure during descent is a disturbance due to the 
increase of atmospheric pressure. It vitiates the 
accurate study of the cardiac muscle which can only 
be examined afterwards during rest. But at the 
same time it is of the greatest importance as an 
observation, for it shows the constant strain to 
which the heart is subject in continually adapting 
itself to different pressures as the airman rises or 
falls. Consequently it explains how airmen come 
to experience cardiac fatigue and asthenia more 
quickly than other athletes. We shall return to 
this point later. 

52 



COLD 

Cold. — Of the origins of air sickness, cold is one 
that is very frequently blamed by airmen themselves. 
The opinion of Morane on this subject has already 
been alluded to. Cattaneo attributes to this cause 
the discomfort which obliged him to stop at Bara- 
dero, about 90 miles from Buenos-Ayres ; this was 
on June 22, 191 1, in the famous flight from Rosario 
to Buenos-Ayres, and at the time the Bleriot mono- 
plane had already carried him over 150 miles. 

He tells the story of how he suddenly experienced 
an intense feeling of coldness throughout his whole 
body; his feet became paralysed, his hands anky- 
losed, whilst from his eyes there streamed frozen 
tears. A sort of inertia, likened by the airman to 
" a dreamy ecstasy," had overcome him and h« 
had only just time by a last effort to land his 
machine before he was completely engulfed in this 
general numbing of the senses.^ 

It is of course well known that cold results in a 
painful sensation of numbness and fatigue, that 
physical as well as moral energy is weakened, and 
that, above all, the desire to sleep becomes impera- 
tive. But in order that these results should become 
manifest, the cold must be considerable and must 
last over much longer periods than are usually 
covered by aeroplane flights. And further, how are 
we to explain the fact that it is during the descent, 
while the organism is moving nearer to the warmer 
atmospheric layers, that the phenomena of air sick- 
ness become most intense? 

There can be no doubt, however, that cold compels 
the heart to sudden and repeated efforts which add 
to its fatigue. Here again, in normal persons it is 

^ La Nacion, Buenos-Ayres, June 24, 191 1. 

53 



THE AETIOLOGY OF AIR SICKNESS 

chiiefly the Mx. tension which shows the clearest 
changes. One of us (Cruchet) carried out the fol- 
lowing experiment during the afternoon of July 12, 
1918. The outdoor temperature stood at 2^]^ C. 
The pressures were registered by a Pachon oscillo- 
meter and are shown in fig. 11. 

The subjects of experiment passed into M. Pouey's 
cooling chamber, which had been kindly put at our 
disposal by his employers. In this room the tem- 
perature stood at 2° C. and the pressures were 
registered in the room itself. The following table 
shows the results : — 



Temp. at270C. 


Temp, at 20 C. 


C 


.. 16 —10 


i8i-ioi 


L 


.. i5i- 9i . 


16 —10 


S 


.. 19 —12 


23 -I2i 


P 


..18-9 


20 -10 


B 


..20 — 9 


25 —10 





.. 24 —10 


.. ^ 30-14 



If we disregard the last pressure taken on an 
arterio-sclerotic individual and which is altogether 
abnormal in its exaggerated reaction both of Mx. 
and Mn., we see that cold causes a rise in Mx. pres- 
sure, whilst the Mn. pressure remains nearly con- 
stant. 

We have therefore to take into account the direct 
action of cold on the arterial tension in raising the 
Mx. pressure. This effect will be more noticeable 
as the airman rises and the cold becomes more 
intense. Thus the effect of temperature must be 
added to the extra cardiac effort which is demanded 
by physical exertion and sustained voluntary atten- 
tion, and which normally results in h)rpertension. 
There is, that is to say, an additional cause of 
hypertension to those which we have already con- 
sidered. 



54 



COLD 



The heart has still another call upon its energy 
and therefore still another source of fatigue has 
been disclosed. 



The effect of co/cf 




The effect of Ment^/ 

a ^ at rest 

s = dur/n^ attention 

a'^at rest as^in 




•— f^c/fse rate 

B3 Arterial pnSss^re in Cm of tfg (fi^ininja) 

nZJ '» »» w '» (fWaxima) 

Fig. II. 

The effect of cold is to cause a distinct rise of both 
Mx. and Mn. pressures, the rise being much greater in the 
case of Mx. Under the influence of mental strain, although 
there is marked rise in Mx. pressure, it is scarcely notice- 
able in the case of Mn. 



55 



THE AETIOLOGY OF AIR SICKNESS 

Mental Strain.— There is no denying that the 
attention demanded by the control of an aeroplane 
also has its influence, an influence which is more 
pronounced as the work of control is harder and 
more prolonged. But once again, if one may judge 
from the observations on mental strain (learning of 
a lesson, listening to an address, explaining a 
problem, &c.), it is still the Mx. pressure which is 
increased while the Mn. remains practically thie 
same. 

Fig. II shows the results of observations made 
on May 29, 1919, upon four typical subjects. H., 
a house physician, is trying to recollect the branches 
of the internal maxillary artery; Cr. is listening 
with sustained attention to a story of events in 
Odessa; B.-G., a Colonial physician, is calmly 
relating a war adventure without any gesticulation; 
C. is a fifteen-year-old schoolboy who is learning 
Eis lesson of Ovid. 

Emotion. — Although emotion is not peculiar to 
the airman, it will be readily admitted that in his 
particular case it plays an important part, especially 
when he is new to his calling. 

All apprenticeship, whether learning to swim, to 
cycle, or to drive a motor-car, is a source of 
emotion. It is the stage of uncertainty, of inexperi- 
ence, a source of fear and uneasiness and a period 
when lack of confidence in oneself helps to increase 
the emotion. The various emotional factors in 
aviation have been successfully analysed by Dr. 
Ferry. 

If some, sheltering themselves behind their airmen's 
pride, confidently deny that they ever experienced the 
least uneasiness, there are others, many others, who on 
the contrary admit that they were subject to the changing 
influences of their training. 

56 



EMOTION 

In spite of their imagined self-assurance, emotion over- 
took them during their first flights, a fleeting sense of 
fear pursued them, making them for the moment nervous 
or seeming to paralyse their movement. In order to ex- 
plain these phenomena they referred to the apprehension 
resulting from such events as the presence of hot-air 
currents, high wind, the passage through clouds, the tilting 
of the machine necessary in turning, and the constant 
turning in the same direction during descent. Some say 
that they have suffered from temporary loss of^ conscious- 
ness of which they were only aware through its results. 
One such result described to us was the abnormal ampli- 
tude of oscillation which was observed in the altmeter. 
Another is quoted by Jacques (of Nancy) as follows : " A 
good pilot with a long experience of aerial navigation, 
subject to loss of consciousness in the aeroplane, trusting 
to the stability of his machine, was accustomed to let loose 
the controls during the two or three minutes his fainting 
attack lasted." 

Most airmen are emphatic in describing a strange feeling 
of anxiety of short duration which is associated with the 
lifting of the machine on a hot-air wave. It is said to 
be even more noticeable when the aeroplane falls into a 
trough of cold air. On such occasions, they say, their 
strength seems to leave them, their legs grow weak, their 
movements erratic; they become pale, with ringing in the 
ears and momentary haziness of vision ; dizziness may even 
pass into unconsciousness if this fall into the air trough 
is prolonged. 

We ourselves have experienced and carefully observed 
this sensation. It is characterized by a certain stoppage 
of breathing during inspiration and with slowing of the 
heart, which recovers speed as soon as the source of the 
disturbance is removed. It is the same sensation as is 
felt during the rapid descent of a lift. In the case of 
the airman, alone in space and subject at this time to the 
constraint of fear, this sensation acquires an unusual in- 
tensity, an intensity moreover which is in proportion to 
the greater amplitude and abruptness of the movements. 
It may have very serious consequences. ^ 

The instances which are given do not all show 

the same degree of emotional reaction. In some 

cases the subject appears to have acquired complete 

tolerance of danger. Such a one is the pilot quoted 

1 J. G. Ferry, loc. cit., pp. 46-48. 

57 



THE ETIOLOGY OF AIR SICKNESS 

by Jacques who in the presence of peril gave evid- 
ence of the most complete presence of mind. But 
it is to the highest degree probable that all airmen 
do not react in this way, and it is even likely that 
this airman himself was aware of a certain degree 
of emotion the first time that he experienced dizzi- 
ness, and that in time he learned to get over it. May 
there not be many who, finding themselves con- 
fronted with sudden and unexpected bodily distress, 
have fallen victims to their own emotion, and losing 
control over their action, have sped earthwards to 
the final crash? 

Emotion is not present only in the young and 
inexperienced. It may also be found in those who 
are old hands at the business when they are tired 
and have no longer confidence in themselves. 

Emotion may momentarily increase the arterial 
tension, as Messrs. Etienne and Richard have quite 
recently pointed out.^ But it cannot be supposed 
that every airman necessarily experiences emotion 
each time that he comes to earth. Moreover, as 
soon as he has landed the intensity of emotion is 
dissipated and the result in hypertension tends like- 
wise to disappear if emotion alone is its cause. 

Finally, in this case, as in the last, when the 
<luestion of mental strain was under consideration, 
it is particularly the Mx. tension which is increased, 
the Mn. remaining almost constant. But in both 
eases there results a manifest cardiac fatigue which 
must be taken into consideration along with other 
eauses of alteration in the blood-pressure. 

Oto-rhino-pharyngeai Lesions.— B e s i d e s the 

^ G. Etienne and G. Richard : " La pression arterielle et 
les emotions de guerre " {Paris medical, August 9, 1919, 
p. 109). 

58 



OTO-RHINAL-PHARYNGEAL LESIONS 

general disturbances which have just come under 
our notice, we ought to give a separate place to 
the consideration of local lesions which give rise to 
air sickness, such as disease of the ear, nose or 
pharynx, which have an effect on the auditory sense. 
It is now a considerable time since writers on avia- 
tion first insisted upon the importance of a perfect 
auditory system in the airman. 

The only question with which we have to deal is 
as to whether it is possible that these lesions, even 
when they are so sHght as not to be noticed, are 
capable of causing air sickness by themselves. 
Messrs. Marchoux and Nepper, after carrying out 
a large number of experiments under the Paul Bert 
bell, believe that they are. 

All our observations, they say, lead us to believe that 
great importance is to be attached to the integrity of the 
rhino-pharyngeal mucosa. Any obstruction which prevents 
the rapid establishment of pressure equilibrium between 
the cranial air spaces and the surrounding atmosphere in- 
volves the possibility of a whole series of misfortunes of 
which pain is one of the least and syncope one of the 
most serious. All become more marked as the airman 
approaches land and at a time when he must need his 
faculties to assure his safe landing. Whilst the atmo- 
spheric pressure decreases by lo cm. of mercury between 
o and 1,000 metres, it does not vary more than 4 cm. 
between 6,000 and 7,000 metres. It is therefore in the lower 
layers of the atmosphere that the defect in equilibration 
is most felt. Usually the ascent is accomplished without 
serious mishap. The cavity of the middle ear empties 
itself with comparative ease; but during the descent even 
slight inflammations and a fortiori chronic or severe lesions 
result in the adhesion of mucous surfaces and create a 
blockage which becomes firmer as the difference of pressure 
is more marked. 

It will readily be understood how that under these con- 
ditions the airmen unconsciously set a limit upon the 
height of their flight, being aware of the accidents to 
which they are exposed by recompression. We say un- 
consciously, for most of them do not explain to themselves 

59 



THE ^ETIOLOGY OF AIR SICKNESS 

their motive for this limitation. They nearly always 
attribute it to the falls from which they have suffered. ^ 

According to this argument, a person who is quite 
healthy, so far as his rhino-pharyngeal mucosa is 
concerned, ought to be secure from the common 
disturbances which constitute air sickness. It does 
not seem to us that the question can be considered 
quite in this light. 

A normal person with perfect integrity of his oto- 
rhino-pharyngeal cavities may very well overtire his 
cardio-vascular system if he travels too fast through 
space and subjects his organism to too rapid changes 
of atmospheric pressure. The tympanum is the first 
membrane to suffer and to give rise to pain on 
account of its situation between two constantly un- 
equal pressures which are trying to arrive at equili- 
brium. 

Objectively a red margin may be seen along the whole 
length in front of and behind the handle of the malleolus. 
Moreover, there is intense congestion of the upper part 
of the tympanum which constitutes the membrane of 
Shrapnell. This appearance is identical with that which 
is caused when a retracted tympanum is rectified by in- 
sufflation of air into the middle ear. It is a good indica- 
tion of the successive movements of repulsion and re- 
traction which. the tympanum must be subjected to during 
flight under the influence of wind shock, changes of 
atmospheric pressure and the regulating movements of 
deglutition. 

In healthy ears these disturbances are transitory; in 
short flights they disappear immediately after landing. 
After long flights a slight buzzing and a degree of deafness 
may persist for some hours, even as long as a day, but 
rarely more. 2 

1 Marchoux and Nepper, Soc. de Biol., loc. cit., pp. 
670 and 672. 

2 P. Lacroix, "Les reactions de I'oreille chez les 
aviateurs pendant les vols " {Bull, de VAcad. de MSd., 
January 16, 1917, p. 95). 

60 



SPEED 

An airman therefore whose naso-pharynx is per- 
fectly normal, is still liable to subjective and objec- 
tive reactions of otic origin. It is evident that if he 
overtires his tympanum by rising and falling too 
rapidly, he v^^ill induce a state of inflammation 
mechanically, and this inflammation will itself 
aggravate the phenomena which he experiences. 

This is not to say that the auditory apparatus 
alone reacts to changes of atmospheric pressure. 
The whole cardio-vascular system shares in this 
reaction. If the effect is here less visible, it takes 
place none the less, and we believe that it also plays 
its part in the accidents to which we have drawn 
attention. 

No doubt pain in the ear, like all painful re- 
actions, may result in hypertension. But once 
more, this hypertension concerns the Mx. alone 
and not the Mn. It is, as we have said before, 
the Mn. pressure in which we are particularly 
interested. 

Speed. — In the same way the phenomena due to 
the preceding factors are certainly aggravated by 
speed which in itself is insufficient to produce it. 

Speeds of 50 m.p.h., and even of 60 m.p.h. and 
more are registered every day, either in motor-cars 
or on motor-cycles, on the straight track or the 
racing course, and none of these discomforts have 
yet been discovered. It must be added that airmen 
flying at similar speeds, but without passing an 
altitude of 1,000 metres, experience scarcely any 
ill-effect. On the other hand, when these same air- 
men have been obliged to rise to 2,000 metres and 
to descend again immediately, they are overcome 
by extreme fatigue, lassitude and buzzing in the 
ears. They have no longer any certainty in the 

6t 



THE ETIOLOGY OF AIR SICKNESS 

control of their machine and they have that sensa- 
tion which was experienced by Vedrines in the 
Paris-Madrid flight after crossing the Guadarrama 
at 2,000 metres — a sensation of impending failure 
of the heart. 

This observation has almost the value of an ex- 
periment. It seems, indeed, that accidents are 
determined by too sudden a change of atmospheric 
pressure. Facts of the same kind are of common 
occurrence, although very few have paid attention 
to them before we brought the subject forward. 
We may give some examples : aeronauts had ob- 
served the tendency to sleep (Arym); and others, 
like Soubies, had noticed that in descent, especially 
when this is rapid, there appeared a phenomenon 
as distinct as it was common, which consisted in 
a high auricular tension accompanied by deafness, 
which' was apparent for several hours after landing. 
Again there is the experience of tourists coming 
down steep mountain sides in the funicular railway, 
particularly from the descent of the Jungfrau.-^ 
Then there are motorists like Eugene Renaux and 
Senouque, who describe buzzings in the ears after 
too rapid descent from the col de Ceyssat (3,000 ft.), 
or Latham relating how in Kabyle one of his pas- 
sengers was taken ill in a downhill journey of 1,000 
metres drop. Cyclists on excursions in the moun- 
tains fall asleep as they descend on their machines, 
as we learned from a reliable source at Lyons quite 
recently. ** One day," our informant tells us, ''I 
leant instinctively towards my nearest companion 
as though to sleep upon his shoulder. He caught 
hold of me firmly, just as I was about to swerve 

1 Cf. note, p. 6. 
62 



OTHER FACTORS 

and fall." Finally, according to an observation of 
Abadie (Bordeaux), the skiers have similar experi- 
ences. During an excursion in the Pyrenees he saw 
a young lady suddenly brought to earth by over- 
powering somnolence. It v^as in the course of a 
long and steep run nearly a mile in length. 

Andre Gounouilhou, an airman, has also told us 
that his most extreme sensations of auricular dis- 
tress and buzzings did not occur in the course of 
his numerous aeroplane flights, nor during his 
balloon ascents, but on a certain day when he was 
returning very fast in a motor from golfing at Nice, 
the golf course there being 900 metres above the 
town. 

Finally Dr. Ferry has demonstrated the import- 
ance of speed by the following typical example : — 

It was a pilot of the Farman biplane, the passenger of 
a very clever monoplanist on a Bleriot machine, who (in 
1914) related that after half-an-hour's flight at 1,800 metres 
and a rapid descent in a close spiral he experienced 
sensations such as he had never known before. In this 
case they are due to the greater speed in ascent and 
descent.^ 

Other Factors-— Other factors have been held 
responsible for air sickness. 

The influence of the wind with violent air currents 
has been inculpated (Garsaux); also renal insuffi- 
ciency (G. Ferry) and even adrenal insufiiciency 
(G. Ferry, Josue); digestive disturbances resulting 
from " incomplete digestion " (Garsaux) and cardiac 
asthenia (Josue). 

None of these factors is peculiar to airmen and 
they should only be looked upon as predisposing or 

^ J. G. Ferry, loc. cit., pp. 61-62. 

63 



THE -ETIOLOGY OF AIR SICKNESS 

favouring causes, the list of which might still be 
considerably lengthened. We have thought it our 
duty to limit ourselves to the consideration of the 
most important factors in appreciating the value of 
which there is real interest. 

OrsGUSsion and Conclusions.— The various pre- 
ceding causes are subordinate to changes of atmo- 
spheric pressure, changes which are themselves 
exaggerated by too great speed of the aeroplane 
in rising, and especially in descent; herein is the 
first and essential factor. 

Clearly the organism reacts physiologically to 
these pressure changes by phenomena connected 
with the circulatory system. To us the hyperten- 
sion of the Mn. during a sudden descent appears 
to be one of the most remarkable of these pheno- 
mena. If the individual is in perfect health and 
travels through the air at a moderate speed, the 
disturbances of air sickness which result from his 
movement pass unnoticed, so insignificant are they. 
If, on the other hand, he ascends or descends too 
rapidly, the disturbances become more marked and 
the hypertension of the Mn. is plainly recorded. 

This hypertension during rapid descent now 
appears to us an incontrovertible fact ; it has always 
been observed by those authors who have placed 
themselves under the same conditions of experi- 
ment and observation as we have. Even Messrs. 
Marchoux and Nepper, though they do not attach 
any importance to this hypertension, nevertheless 

found it constantly present in the airman A 

during his enclosure in the Paul Bert bell. Their 
observations on him were Mx. i8, Mn. 14, instead 
of Mx. 17 and 16 and Mn. 13 and 12, these observa- 
tions being taken after a return from pressure at 

64 



DISCUSSION AND CONCLUSIONS 

5,500 metres to sea-level in six minutes, which 
corresponds to a vertical rate of over 35 m.p.h.^ 

Mr. Garsaux has written to tell us that in the 
diving-bell recompression experiments at Saint-Cyr, 
carried out at a rate of 25 to 30 m.p.h., he has 
observed hypertension also, except on one occasion. 
Also that in July, 1917, an airman who was 
examined by him after a parachute descent of 600 
metres from his aeroplane, showed a very marked 
hypertension. It is true that this was noted for 
the Mx. pressure only. 

Finally, in the case of Fonck (also from the re- 
cords of Garsaux) pressure of Mx. 19, Mn. 10 is 
noted on his arrival, against Mx. 15, Mn. 9 at his 
departure. This was on the occasion of an attempt 
at record-breaking in height in the year 1919, when 
he reached 8,800 metres and came down again in 
13 minutes as the result of failure in his sparking 
plug.2 

We are particularly anxious to draw attention to 
the fine research of F. Villemin who, as the result 
of observations in an aeroplane both on himself and 
on various pilots and observers, has established in 
the clearest and most decisive way the existence of 
minimal hypertension on landing. 

At low altitude, he says, the vasomotor reactions are 
of little importance. This is shown by the slight reaction 
of the Mn. At high altitudes, on the other hand, the Mn. 
always shows a marked increase on landing. This is 
evidence of persistent vasomotor reaction. 

This author's conclusions are in exact agreement 

^ Societe de Biologic j session on June 21, 1919, p. 672. 

2 This speed (about 25 m.p.h. only) is fairly slow for 
a person in training, and the subject of the experiment 
was not under normal conditions, inasmuch as he was 
breathing oxygen at the time. 

65 



THE ETIOLOGY OF AIR SICKNESS 

with our own, and they are not only confirmatory, 
but also complementary.^ 

It seems, therefore, that the minimal hypertension 
in rapid descent is one of the most customary of 
organic reactions, belonging to the same categorj^ 
as those other phenomena — headache, auricular 
pain, sleepiness and syncope — which are the essen- 
tial characteristics of air sickness. 

These disturbances are clearly due to changes in 
atmospheric pressure, or, to put it more precisely, 
they are due to a too rapid recompression following 
upon the decompression which takes place during 
the ascent. 

As for determining the esoteric causation of the 
air-sickness syndrome, it must be remembered that 
the origin of mountain sickness is still in dispute. 
Yet nobody questions to-day the genuineness of 
mountain sickness. 

At the same time the ingenious experiments of 
J. Tissot are worth recording, as are also those by 
Goldstein and Zuntz. The former was able to in- 
duce headache, dizziness, visual disorders and a 
localized sensation of discomfort in the thorax. 
The two latter obtained hypertension by administer- 
ing normal air after a course of air impoverished 
in oxygen. It follows that disturbances which recall 
those of air sickness, result from a too rich supply 
of oxygen following upon its privation. 

But auricular pain, so constant a feature of air 
sickness, is absent in these experiments. Marchoux 
and Nepper obtained similar results by placing air- 
men in a mixed atmosphere of nitrogen and oxygen 
in the proportion which corresponds to the nonnal 

^ See Societc de Biologic , session of June 21, 1919, pp. 
C96 to 706. 

66 



DISCUSSION AND CONCLUSIONS 

atmosphere at 7,000 to 8,000 metres. Their subjects 
were furnished with an oxygen apparatus and en- 
closed in a Paul Bert bell, and decompression pro- 
gressively induced so as to correspond to altitudes 
of from 7,000 to 8,000 metres, recompression rapidly 
succeeding at a speed of first 35, and then' 15 m.p.h. 
The same phenomena were observ^ed by these 
authors as in the case of individuals who underwent 
the same conditions without the respiration of 
oxygen, that is to say, they experienced headache, 
auricular pain with neuralgia along the sterno- 
cleido-mastoid muscles, buzzings in the ear, some- 
times dizziness and even nausea and threatened 
syncope. 

In the last analysis, therefore, we are brought 
back to the factor of speed, which seems to play 
the essential part in the aetiology of air sickness, 
as we have maintained since the year 191 1. 



67 



TRAINING AND OVERWORK IN THE AIRMAN 



CHAPTER IV. 
Training and Overwork in the Airman. 

It might seem^ that the renaissance of Athletics, 
to the furtherance of whose ends new schools are 
founded almost daily, has at last provided us with 
precise directions for the training of her devotees. 
In other words, that being now furnished with 
the means of determining the exact moment when 
fatigue is about to appear, we have learned also how 
ft may be avoided. Truth .compels us to state that 
no such thing has happened. We still live in an 
age of pure empiricism. Very few professors of 
physical culture worry themselves about their pupils' 
health, and the pupils are even less careful of them- 
selves, for they scarcely ever consult their doctor 
lest some defect should be discovered which would 
prevent them from devoting themselves to their 
favourite pastime. When by chance they do submit 
to a medical examination, they usually take no 
account of the doctor's advice, but hasten away to 
the bonesetter round the comer or to the masseur 
across the road. These, to their great joy, confirm 
their youthful wisdom against the doctor's counsel. 

In Anglo-Saxon countries the athletes are a good 
deal more intelligent in this matter. It would be 
easy to multiply statistics collected by doctors from 

^ See Petite Gironde, May 5, 1914. 
68 



Try. 

TRAINING AND OVERWORK IN THE AIRMAN 

observations made on experts in different sports 
which are popular at the present time, such as flat- 
racing, cycHng, rowing, football, tennis and cricket. 
Sir Thomas OHver (of Glasgow), Professor of the 
Faculty of Medicine in Durham University, recalled 
certain truths some years ago which it is excellent 
to know and better still to remember.^ 

The value of athleticism to the individual, says this 
eminent observer, is in a large number of instances over- 
rated. Athletic exercises doubtless confer physical advan- 
tages, they brace a man up, they make him more resistant 
to fatigue, and they keep him out of mischief, but they 
do not confer immunity to disease. It is a well-known 
fact that it is frequently the healthiest-looking men and 
women, also the most florid, who succumb most readily to 
fever, to acute illness, and who cannot go through a 
serious surgical operation so well as the slimly built and 
delicate. Many athletes whom I have known have died 
from pulmonary tuberculosis, others from heart disease. 

Violent forms of sport are not in every case the 
most profitable. In a certain number of young men 
they induce cardiac hypertrophy, more especially of 
the left ventricle. This enlargement of the heart, 
which may be Httle regarded at the age of twenty- 
two, must be looked upon more seriously in the 
thirties. It has even been shown by medical experi- 
ence that English footballers begin to lose some of 
their form after the age of twenty-five. 

Forty years ago Dr. John E. Morgan inquired 
into the history of those crews which had contested 
the Oxford and Cambridge Boat Race from 1829 
to 1869. Of 294, seventeen had cardiac lesions re- 
sulting from overstrain which dated from their 
rowing days. These observations have since been 
confirmed by others. 

1 The Lancet J April 4, 191 4. 

69 ^ 



TRAINING AND OVERWORK IN THE AIRMAN 

If to these facts are added the occurrence of 
sudden death in the case of cyclists, flat-racers, or 
other athletes, during or at the end of their efforts 
— not to mention the tragic fate to which even in 
our days Marathon racers are sometimes destined 
— it is certain that the conduct of all sport, if it is 
to be safe and profitable, demands a competent, 
attentive and constant direction. 

It is evident that these fatahties are exceptional 
and their importance must not be exaggerated. On 
the other hand. Dr. Morgan's figures, which might 
be more or less applied to all forms of sport, un- 
doubtedly teach us a lesson, showing as they do 
tTiat out of 100 young people who go in for racing, 
39 improve their health, 55 obtain no physical advan- 
tage, and 6 suffer real hurt. Therefore, if it were 
possible by means of an appropriate supervision to 
eliminate this loss, small though it is, athleticism 
would enter upon an entirely new and progressive 
phase. 

In point of fact, there has not yet been formulated 
any really scientific method of determining the signs 
which indicate the commencement of fatigue and 
the necessity for rest. 

The importance ol keeping within the limit of 
normal fatigue has been a source of continual care 
to all who have written on physical culture or who 
have tried to direct a system of training. In a book 
by F. Heckel there is found the following passage : 

From the time when sweating makes its appearance and 
50 long as it is maintained with its customary warmth, 
exercise becomes easier and more agreeable. The rhythm 
of exercise is increased and more difficult exercises, re- 
quiring a maximum effort, are undertaken. At such a 
time the limit may easily be passed and this limit should 
be carefully established beforehand. It must be sought 

70 



TRAINING AND OVERWORK IN THE AIRMAN 

for in every case by careful experiment, and the dosage 
fixed according to the fatigue reaction or the persistence 
of well-being. 

So far so good. But how are we to know just 
when this fatigue reaction has been reached or ex- 
ceeded and to what extent? This is the whole 
question, to which none but evasive replies are ever 
given. 

The research which has been carried out up to 
the present time has registered results which are 
certainly very instructive from the scientific point 
of view, but they are of no practical importance. 
Both Messrs. H. Aurenche and G. Loucheux, 
taking up work which has been known for a long 
time and which was grist to the mill of Tissie and 
other physicians more than twenty years ago, com- 
municated in Biologica in the year 1914 the results 
of physiological reactions to fatigue, measured in 
four cyclists (Hourlier, Rutt, Walthour and Verri). 
The observations were made during the second fort- 
night of January, 1914, at which time a six-days* 
racing festival was taking place at the Palace of 
Sports in Paris. There is scarcely anything new to 
be learned from these observ^ations. They show 
that under the influence of sustained muscular 
fatigue the daily output of urine is diminished, re- 
sulting at first in a decrease in the quantity of 
urinary constituents eliminated; then towards the 
end when fatigue becomes more extreme, the 
elimination of these constituents is increased. In 
the same way the examination of the pulse shows 
a constant rate (from 60 to 80 per minute) during 
the first days; then when fatigue becomes more 
marked it increases in speed to 90, 100, or even 
more. 



71 



TRAINING AND OVERWORK IN THE AIRMAN 

These facts, though certainly very interesting, do 
no more than confinn those which have already 
been published, and like these former results, they 
only show us the physical effects to which fatigue 
gives rise. They do not tell us what really would 
be much more useful for us to know, the precise 
moment when in a given subject the organism is 
on the point of experiencing this fatigue and con- 
sequently ought to have procured rest for itself. 
It is to that end that every system of physical cul- 
ture worthy of the name ought to be aiming. At 
the same time overstrain is avoided and the athlete 
conies under the best conditions for producing at 
the proper time his maximum effort. 

Now this practical method is actually in existence, 
as we have shown above in speaking of Professor 
Pachon's criterion of training. Unfortunately, it 
was scarcely used at all in the case of airmen during 
the war. 

One writer only, Mr. F. Villemin, seems to have 
appHed Pachon's method to aviation. But as he 
himself says, *' It necessitates in the first place a 
complete knowledge of the pressure regime of the 
subjects under examination, and in addition a series of 
examinations must be carried out after every flight, 
especially after flights at high altitudes for pro- 
longed periods."^ 

From a study of about 500 observations he has 
been able to establish in the case of aiiTnen appren- 
tices that during the first phase of adaptation there 
is a lowering of Mx. pressure and a tendency for 
the Mn. pressure to be slightly increased. These 
pressure changes are accompanied by a quickening 

1 F. Villemin : Loc. cit., pp. 703 and 705-706. 
72 



PHYSICAL OVERSTRAIX 

of the pulse and a diminution of Pachon's oscillo- 
metric index. 

In the second phase, when adaptation may be 
considered complete, the Mn. remains stationary or 
is slightly diminished, the varying pressure returns 
to its first value, the oscillometric index increases 
without, however, reaching its original value, and 
the pulse returns to normal, even in some cases to 
a figure somewhat lower. 

I think that we are concerned here, Villemin concludes,^ 
with the progress of adaptation and that the final stage is 
marked by a lowering of both Mx. and Mn, pressure, a 
slight reduction of pressure variation, the diminution of 
the oscillometric index and a slowing of the pulse. 

My own observations have convinced me that the most 
stable cardio-vascular systems are those in which the 
pressures are relatively low. The most efficient airmen 
whom I have examined have, as a rule, shown relatively 
low pressures. The Mx. varies between 12 and 13' 5, the 
Mn. between 8 and 9. The pressure variation is 4 to 4*5. 
The oscillometric index does not exceed 3. 

It is necessary that these phases of the airman's 
cardio-vascular training should be clearly understood 
if we are to appreciate the limits within which over- 
training and fatigue show themselves in him. 

Pachon's method should be utilized in conjunction 
with a careful observation of the airman's normal 
pressure changes, as it has been by F. Villemin. It 
is through lack of thes€ precautions that so many 
have suffered from serious overstrain. 

The overstrain to which airmen are subject may 
be either physical or mental. 

Physical Overstrain.— There is no specific form 
of overstrain pecuHar to the airman. His bodfly 
fatigue is of the same kind as other people's, but,, 

^ F. Villemin : Loc. cit., pp. 703 and 705-706. 
73 



TRAINING AND OVERWORK IN THE AIRMAN 

on account of the overwork of the cardio-vascular 
system being perhaps more marked in the airman 
than in other athletes, it shows itself in a more pre- 
cocious manner, is often more enduring, and the 
cardiac musculature is early affected. This fatigue 
is commonly described as the cardiac asthenia of 
airmen. 

Cardiac Asthenia.— Asthenia^ is expressed sub- 
jectively by great lassitude, a sense of extreme 
fatigue, and objectively by hypotension of both Mx. 
and Mn., not only on landing, but especially after 
flight during a period of rest. 

Certainly hypotension of Mx. and even of Mn. 
may be observed immediately after the descent of 
the aeroplane. But for this to take place fatigue 
must be considerable. We have seen that, as a rule, 
the minimum pressure is increased on landing, par- 
ticularly if the descent has been made somewhat 
rapidly. It follows that in proportion as fatigue is 
slight, marked or very considerable, the Mn. may 
be simply raised to a slighter degree or equal to or 
lower than its value measured before flight. F. 
Villemin has also observed that if untrained airmen 
are allowed to fly in spite of their inadaptation, the 
result is expressed by a slighter though more per- 
sistent increase of the Mn., which appears sym- 
ptomatically as organic distress, difficulty in flight, 
and a certain nervous condition. 

This is a useful indication to remember, for it 
provides a rational method of training. But it must 
also be remembered that great fatigue is, according 
to general experience, frankly expressed by an im- 

^ R. Moulinier and R. Cruchet : Fatigue et asthenie 
cardiaque des aviateurs {Sodetg de Biologies June 21, 
1919, p. 680-81). 

74 



CARDIAC ASTHENIA 

mediate drop in both Mx. and Mn., a diminution of 
the oscillometric index and the reduction in the 
pressure variation. The greater the fatigue and the 
resulting weakness of the heart, the longer will 
these phenomena persist through the period of rest. 
They may last for a few Hours or many -days, even 
for weeks and for months. The same observations 
have been made by S. Tara,^ who attributes the 
lowering of arterial pressure (Mx. and Mn.) to 
physical fatigue, resulting from too long voyages 
or from a too severe apprenticeship. 

The first effect of fatigue, then, is to disguise the 
ordinary hypertension resulting from flight : the in- 
creased value of Mn. is no longer obvious, some- 
times there is tachycardia. If fatigue is more 
extreme, hypotension will result. The following 
example illustrates this point : — 





Airman unfatigued 
Minimum 


Airman fatigued 
Minimum 


Before flight 
After flight 


9 

12 


:;; 1 



This hypotension connected with fatigue is not a 
phenomenon peculiar to airmen. As we have 
already said, it is common to every kind of fatigue 
(PP- 35> 36)- But in the airman it acquires great im- 
portance because it comes in close succession to the 
vasomotor reactions which we have described, and 
because it affects an organism which has been 
already exposed to variations of vascular pressure 
through the nature of its work. 

^ S. Tara : Societe de Biologie, loc. cit., p. 7og. See 
also Martin Sisteron : Considerations sur les causes et 
les eflPets de la fatigue en general et de I'usure organique 
chez les aviateurs du front {Paris medical j July, 1919, 
pp. 61-65). 

75 



TRAIOTNG AND OVERWORK IN THE AIRMAN 

This myocardial weakness is shown by percussion 
and the X-rays to correspond with an increased 
volume of the heart^ and even sometimes it is accom- 
panied by '' a slight dilatation of the ascending aorta 
which Hes to the left of the vertebral shadow " (Sous- 
lieut. D., 1917). 

On auscultation the sounds are muffled. Very 
often a soft murmur is heard with the first sound, 
clearer in front of and above the apex than at the 
apex itself, sometimes conducted to the base and 
having all those characters of the muiTnur of cardiac 
asthenia which have been observed and described 
by Lamacq. As our friend has described it, they 
give the illusion during a rapid examination of the 
gallop rhythm and the presystolic murmur of mitral 
stenosis.^ There is even sometimes duplication of 
the second sound at the base and an indefined mur- 
mur in the aortic region which may suggest a slight 
aortitis. These disorders are temporary. We have 
observed them both with and without cardiac dilata- 
tion on many occasions. They disappear after some 
weeks of rest, except in serious cases in which they 
may persist for several months. They are accom- 
panied by instabiHty of arterial pressure, a sign of 
myocardial weakness which may be illicited by a 
method which one of us has described. The method 
consists in placing the arm in a position of elevation 
when an abnormal hypotension both of Mx. and Mn. 
will be observed, the drop amounting to 3-5 or 4 cm. 
of Hg instead of 2 cm. which is registered in a 

^ See also Etienne and Lamy : L'hypertrophie du coeur 
des aviateurs {Societe de Biologic^ June 14, 1Q19, pp. 652-55, 
and previous publications in 191 8). 

2 Gazette hebdomadaire des Sciences medicales de Bor- 
deaux, August, 1906, and February, 1907. 

76 



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77 



TRAINING AND OVERWORK IN THE AIRMAN 



healthy person.^ The examples given on page yj 
make this clear : — 

The same figures may be expressed diagrammatic- 
ally as is done in figure 12. All these clinical sym- 
ptoms are manifestations of a functional disturbance 

Exaggerated, fall of 'pressure with the arm elevated: 
An ex-pression of cardiac debility. 




Variations 
in a 
normal 



I 



» 
I 



Normal 



Arteria/ pressi/r^e /n fat/yoe 

nrreasurements taken at the 

wrist, the forearm beinj D 

turned cfoi/t/nwarcfs; H horizonta/; 

£ turned up ward's 
n 

D 




Fig. 12. 
This diagram is obtained from records taken from five 
of our most successful airmen. It shows that at the time 
of examination there was great cardiac fatigue and that 
rest was imperative. 

Ren^ Moulinier : Variations des valeurs des pres- 
sions arterielles suivant les positions donn^es au membra 
(Journal de physiologic et pathologic generalCj 1917-1918, 
pp. 977-989). 

78 



PSYCHIC OVERSTRAIN 

common to all conditions of fatigue. Their existence 
in the aii-man is especially serious because they may 
be the cause of fatal fainting attacks during flight. 
This consideration makes the prognosis uncertain 
and emphasizes the importance of getting a clear 
conception of them so that the patient may be pre- 
vented from flying whilst he is subject to cardiac 
fatigue and so with his passengers be saved from 
disaster. 

Psychic Overstrain. — In considering the aetiology 
of air sickness, psychic overstrain must be taken 
account of as well as physical. Clearly psychic 
asthenia is not unrelated, at least in some cases, with 
physical asthenia. There are, however, some who, 
in spite of magnificent physique, will never make 
good airmen. In their case it is the mind and not 
the body which gives way. 

In order to understand this psychic asthenia, we 
must picture to ourselves what an airman's work 
consists of, especially in war-time. 

Let us suppose that his apprenticeship is finished 
and that as the result of his training he has been 
able to show the necessary qualifications of a pilot. 
At this stage he is master of his machine and of 
himself. The beginner's emotions are well under 
control. After many weeks* work he understands 
the complicated machinery of an aeroplane. He is 
familiar with its behaviour and at home with the 
various controls and registering apparatus. 

Now when he needs a quiet season of rest from 
the emotions of apprenticeship, he joins his squadron 
and must engage in dangerous fight with the enemy* 

^ R. Cruchet : La crainte du danger chez le com- 
battant {Mercure de France,, November i6 and December 
I, 1918, pp. 193-212 and 431-452). Le courage guerrier 
{Idem, July i, iqiq, PP. 40-54). 

79 



TRAINING AND OVERWORK IN THE AIRMAN 

and adapt himself afresh to situations inspiring fear. 
In this, however, he is successful. 

But the over-emotional life still continues, more 
stressful perhaps than in the cas»e of other com- 
batants. All the airmen of whom we have inquired 
tell us that they know no intellectual work so wear- 
ing to the mind as their duty in flying, whether it 
be a question of reconnaissance, observation, pursuit 
or bombing. Particularly distressing is the constant 
watch which must be kept on the horizon during 
daylight raids. So great is the speed of an aero- 
plane that the pilot can never be sure that an enemy 
will not fall upon him when he least expects it. 
Clouds lend themselves to ambush, and uncertainty 
haunts the way without respite. 

The actual control of his machine certainly involves 
no more than a series of reflexes which in themselves 
cannot produce great cerebral fatigue. But the air- 
man's attention is well occupied with his mission, 
spying out the land, enemy formations, gun posi- 
tions, trains, ammunition dumps, and so forth. 

The work is distressing because it demands a great 
effort of will, the attention being always inclined to 
wander from the duty in which the airman is en- 
gaged to the possibilities of dangers that threaten 
constantly from every side. 

Almost certainly a moment will come during a 
period of great activity when the will wavers. 
Fatigue has robbed the pilot of his former self- 
confidence. He is no longer a part of his machine 
as he was at first. In the end he guides it uneasily 
with a control that is less sure. He attributes a 
greater and greater significance to those little 
physiological phenomena which up to that time had 
passed unnoticed or had failed to excite his interest. 

80 



AIR NEUROSIS 

His confidence lost, he is now on the way to a 
neurosis. 

Air Neurosis. — We do not beheve that a true 
neurosis of airmen^ has any independent existence. 
The phenomena which they experience are precisely 
the same as those which are encountered among 
neurasthenics and psychasthenics elsewhere. 

In those whose neurasthenia is due simply to over- 
work, there is obs-erved a headache which persists 
apart from flight. There is a great desire for sleep, 
though the patient sleeps badly, being wakened by 
nightmares until insomnia results. A sensation of 
great tiredness overwhelms him and his character 
becomes hypersensitive, irritable, capricious, dis- 
agreeable, with a tendency to fits of anger and of 
depression. He complains of inability to concen- 
trate his thought as formerly, ideas escape him and 
there is no order in his rather befogged mind; self- 
confidence has been lost. 

Experienced pilots find flying a pleasant pastime, until 
they have to go through a time of severe strain, when 
every effort must be expended. Their working capacity 
and resistance to the conditions of high altitudes are 
diminished. Flying becomes more and more distressing, 
particularly when a height above i,8oo metres is reached, 
or when the return to sea-level is rapid. How many 
pilots there are of three or four years' standing who can 
only climb with great difficulty to 1,200 metres and who 
even at this height lose confidence in themselves, some 
of them have plainly stated. 2 

In most of these cases, whose condition is due to 
simple overwork and who are without any constitu- 
tional stigma, rest usually sufl^ices to restore tran- 
quility of mind. 

^ B. Cruchet : La nevrose des aviateurs {Journal de 
Medecine de Bordeaux, October 10, 191 9). 
^ J. G. Ferry : Loc. cit., p. 61. 

81 



TRAINING AND OVERWORK IN THE AIRMAN 

But there is also a class of constitutional neuras- 
thenics, more accurately described as psychasthenics, 
in which the effect of flying is to disclose or to pro- 
voke an abnormal psychical reaction which was 
formerly latent. 

Most of the pilot apprentices who are found unfit 
after a few weeks' trial belong to this group. Nor- 
man S. Gilchrist analysed loo cases of unfitness. He 
found eighty-two of these to be due to nervous 
trouble, and of this number forty-four were pupils 
and only twenty qualified pilots. 

The detailed research of this author has shown 
that in 37 to 40 per cent, of cases there is a family 
or personal history of hereditary nervous disorder, 
and in 52 per cent, there have been previous disturb- 
ances of the higher cerebral functions relating to 
memory, judgment, character, emotivity, with obses- 
sions and even hallucinations. ^ 

In this group we observe the preceding morbid 
phenomena in a more accentuated and tenacious 
fonn, as well as obsessions, compulsion, neurosis 
and phobias. 

There is a groundwork of general lassitude, mus- 
cular weakness and physical discomfort. The patient 
complains also of various subjective secretions, such 
as pain or oppression in the epigastrium, abdomen, 
prsecordium and phaiynx. The pharyngeal muscles 
may be contracted giving an ill-defined impression of 
perpetual anxiety. 

At first the appetite and thirst are both increased, 



1 Norman S. Gilchrist : An analysis of causes of 
breakdown in flying {British Med. Journ.j October 12, 
1Q18, pp. 401-403). See also C. Juarros and Antonio 
Perez Nunez (SociSU de Biologic, Session of June 21, 
IQ19, p. 691). 

82 



AIR NEUROSIS 

but neither food nor drink bring the satisfaction 
hoped for. On the other hand, digestion is less 
comfortable than formerly — it occupies a long time 
and is associated with eructations and nausea. Gas- 
tric dilatation and tympanitis are stages on the road 
to complete anorexia. 

The demands to urinate and to defaecate become 
irregular and capricious. The patient, now that 
ordinary food no longer pleases him, whets his 
appetite with excesses of red and white pepper and 
strong drinks. These stimulants give but passing 
relief. He seeks diversion in the charms of wine 
and women, but these in turn soon lose their power 
for he cannot appreciate them as he used to and 
their pursuit leaves him ever weaker and more weak. 

At the least exertion the patient experiences pal- 
pitation and difficulty in breathing. He does not 
seem able to take a full breath and the beating of his 
heart chokes him. Even when resting he is short 
of breath. 

Now thei-e is a great void within tlie brain, sur- 
rounded it seems by the helmet which, though long- 
ago removed, still binds his forehead like a vice, and 
weighs upon his beating temples. Thought moves 
behind a veil or across a cloud of mist as in some 
endless dream. Memory is restive, forming but 
poor images of events both within and without, re- 
calling them with even less success. Rumination 
takes the place of decision. Judgment miscarries, 
hesitating ever between irrational suggestion and 
endless, painful doubt. 

Instability and agitation have replaced the order 
resulting from a firm will. A factitious and blunder- 
ing activity henceforth directs this human organism 
while the personality attends, a drifting, shapeless 

83 



TRAINING AND OVERWORK IN THE AIRMAN 

wreck, the spectator of its own disintegration. Pre- 
sently there appear obsessions, phobias, compulsions, 
sowing in the tortured mind a terrible disquiet. The 
patient, now thoroughly disordered, passes through 
the most paradoxical experiences; at one moment 
indifferent to a real disaster, at the next reacting 
with great violence to the most insignificant event; 
occasionally happy in some futiHty, more often 
plunged in gloom seeking solitude, tortured by 
thoughts of suicide and the fear of insanity. He is 
irritable, hypersensitive, restless, uncontrolled and 
devoid of any self-confidence. More and more worn 
out he seeks in healing sleep a remedy for all his ills. 
But alas ! sleep is slow in coming and wretched in- 
somnia is added to his list of woes. 

This picture is coloured in the case of airmen by 
certain special features. As with all combatants his 
loss of self-confidence and his indecision urge him 
to throw off the cares of responsibility, especially if 
he is a pilot. He fears lest he will fail in his duty 
or risk a comrade's death. He reproaches himself 
with having been less diligent in his country's ser- 
vice than he should have been. Some observation 
he thinks he may have missed, or spoiled some 
photograph; through his fault this or that has taken 
place. Sometimes even delusions of persecution 
haunt him : it is intended to sacrifice his Hfe. . . . 

Phobias assail him — fears of death or of accident 
in starting or on landing. When the time comes 
for another flight an overwhelming fear confronts 
him and engages in violent conflict with his sense 
of duty. He conquers it in the end, but each time 
the will loses ground and the day must come when 
he will admit himself beaten. 

If he succeeds in setting out on his flight he is 

84 



AIR NEUROSIS 

pursued by worries. His motor does not seem to 
be running well, he is anxious about a possible 
adversary, or distracted by thoughts of air sickness 
and kindred disorders. Thus in spite of himself he 
will limit his expedition to the minimum eifort, often 
he will never attain even a moderate altitude. 

Many airmen have passed through this martyrdom, 
which they scarcely dare speak of even to the doctor, 
putting down to idleness what is clearly the result 
of an overtired brain. In this, as in all arms of the 
service, there have been men who have stood too 
long in the breach without any mental rest. Many 
of them, faced with the possibility of being thought 
" funks " and " slackers,'' have set out in secret dis- 
tress upon some mad adventure or in the course of 
ordinary duty, knowing what was bound to befall, 
yet preferring a glorious death to groundless sus- 
picion. There have been in this long war more un- 
noticed heroes than can be easily imagined. 



8s 



AIR HYGIENE 



CHAPTER V. 

Air Hygiene. 

The Contra-indications to Flight. 

The disturbances due to asthenia and consequent 
upon overwork which we have just considered 
might all be avoided if the progress of training- 
could be properly controlled. 

It is now some time since our attention was drawn 
to this point. Ever since our first communications 
in 191 1 we have warned against errors of training, 
overwork, and mistaken rates of speed. 

An airman who wishes to compete in altitude tests ought 
to train himself gradually and methodically, not only to 
accustom his organism to the variations of atmospheric 
pressure, but also to prepare his muscles for endurance and 
against fatigue; he ought also to go easy both in rising 
and in the descent.^ 

Air Hygiene. — Since 191 1 we have insisted upon 
the candidate for flying being : — 

of good physique, having especially good sight, perfect 
hearing, and possessing uncommon morale. He must be 
warmly clad and capable of withstanding cold. Above 
2,000 or 2,500 metres he should take oxygen inhalations.^ 

The experience of the war has shown the wisdom 
of this advice. 

As far as protection against cold is concerned 
there have been constant improvements introduced 

1 R. Cruchet, Rtvue Scientifiq^e, December, 9, 191 1, 
lee. cit. 

86 



AIR HYGIENE 

ever since the beginning of the war. Airmen are 
now carefully clad and are warmed automatically by 
various apparatus ingeniously contrived so as to 
carry warmth to every part of the body including 
the extremities of hands and feet. 

The helmet has also undergone useful change. 
The lifebelt should be so arranged that it will not 
cause abdominal injury when the wearer is roughly 
shaken. 

Great progress has also been made in the direction 
of oxygen inhalations. We will confine ourselves to 
a mention of the Garsaux automatic breathing- 
apparatus which has been in use in the French Air 
Service for many years and with which the height 
champions Fonck and Casale made their essays. 
There is nov/ a tendency to employ a mixture of 
carbonic acid and oxygen in place of pure 
oxygen. This was suggested by Aggazzotti. 
It will be remembered that the Italian physiologist 
was able, during his first experiment under a 
pressure bell, to attain 140 mm. of Hg — correspond- 
ing to an altitude of 13,500 metres. He breathed 
II litres of a mixture containing 67 per cent, 
oxygen and 12 per cent, carbonic acid. He re- 
mained at this pressure for eighteen minutes with 
clear mind, normal strength and without any cardiac 
papitations. The respiration rate was 22. 

The gas mixture used in the second experiment 
contained 67*8 per cent, oxygen and 13*4 per cent, 
carbonic acid. The pressure fell to 122 mm. of Hg 
— an altitude of 14,600 metres. No disturbances 
resulted. The mind was clear, sight normal, move- 
ment unconstrained. There was no tremor of the 
lips, no hot flushing of the face. 

Paul Garsaux, drawing his inspiration from this 

87 



AIR HYGIENE 

work, has invented an apparatus which administers a 
mixture (13 parts of carbonic acid to 100 parts of 
oxygen) in doses proportionate to the height reached. 
He has observed that at 8,000 metres much better 
results are obtained by the use of pure oxygen.^ 

As a matter of fact the problem will never be 
satisfactorily solved until crew and passengers sitting 
in an air-tight cabin shall breathe at all altitudes an 
atmosphere practically identical with that at sea 
level. Rateau's method, which is in the experimental 
stage and on the way to success — for the tests 
carried out are conclusive enough — solves this prob- 
lem in a most ingenious manner. In it the exhaust 
gases are used to drive a turbine. This turbine 
forces air under pressure into the cabin containing 
travellers and crew. 

Not only will the human beings on board be bene- 
fited but also the motor which, placed in this same 
cabin, will absorb the air needed for its combustion 
at a pressure corresponding to that at sea level. It 
is calculated that the aeroplane will be able to rise 
without difficulty as high as 15,000 metres or more 
and that at this height it will be able to double its 
speed. This will be of great practical importance, 
as will readily be seen. 

Lastly we have to consider the auditory apparatus. 
It cannot be repeated too often that as his ears are 
the most vulnerable part of the airman's body he 
should look after them and protect them with the 
greatest care. 

Obstruction of the auditory meatus diminishes 
the painful intra-auricular sensations and the buz- 
zings. Old hands who are teaching pupils to fly 

1 SocieU de Biologie, June 14, 1919, p. 646. 
88 



AIR HYGIENE 

advise them to insert a plug of cotton wool in the 
opening of each ear.^ MM. Marchoux and Nepper 
have also observed that when a cork is made to fit 
exactly the outhne of the external auditory meatus 
there is a diminution in the painful phenomena 
experienced in recompression under the "Paul Bert 
bell. 

The movements of ^deglutition are also useful in 
lessening pain and buzzing in the ear. Another 
manoeuvre which has the same effect is that of keep- 
ing the mouth half open so as to allow the air 
pressure to arrive at an equilibrium as rapidly as 
possible. Valsalva's test is also to be recommended 
in rising and Toynbee's in the descent.^ 

General Advice. — The general hygiene of the air- 
man scarcely differs from that of other sportsmen. 

As in the case of all other forms of exercise, the 
younger he is the better he will be able to adapt 
himself to it. The best pilots are those who begin 
to learn before they are twenty. It is considered 
that after 30 or 35 flying is not to be recommended — 
at any rate not in excess. 

The rules of training must be observed by the air- 
man more strictly than by anyone else. There must 
be no long evenings, for a long sleep is always neces- 
sary to rest the tired nervous system. Alcohol and 
tobacco are permitted only in very small quantities, 
if at all, lest the often overworked arteries suffer 

^ Jacques, of Nancy, believes that these phenomena 
result from trauma due to the noise of the motor, which 
causes a tympano-labyrinthine hyperaemia. The strong 
wind has a contributory action. 

^ Valsalva's manoeuvre consists in an expiratory effort 
with the nostrils pinched between the fingers and the lips 
firmly closed together. In Toynbee's, the nose and mouth 
are closed in like manner, but saliva is swallowed in the 
place of an expiratory effort. 

89 



AIR HYGIENE 

from early sclerosis. And for the same good reason 
meals must be of moderate size and the sex appetite 
must also be kept under constraint. 

There is no need for us to recall the importance of 
avoiding both physical and psychical fatigue, emo- 
tional experience and brain work must be cut down 
to the minimum during periods of great aerial 
activity. 

Acrobatics should be forbidden, especially when 
they are of such a kind as to result in rapid changes 
of pressure. Speed in descent should never exceed 
twenty miles an hour and should be limited from 
eight to twelve miles per hour below 2,000 metres. 

Airmen need regular intervals of rest. Ferry 
would give them three weeks rest after every four 
months. But a more logical method would be to 
order a holiday after so many hours of flight. A 
regular medical examination under the strictest 
scientific conditions is moreover essential, in order 
that the physical condition may be ascertained. 

The Principal Contra-indications to Flight. 

Cardio-vascular System. — The heart and circula- 
tory system must be perfectly normal. Any gross 
cardiac or circulatory lesion is an absolute contra- 
indication. Sufferers from constitutional asthenias 
of the circulation cannot be passed; if asthenia is 
accidental, resulting from overwork or fatigue, they 
must be ordered to rest and not allowed back on the 
active list until completely recovered. 

Sufferers from hypertension are likewise not in a 
good condition to face hard service. Perhaps if 
they can claim to be cured and if due regard is had 
to the medical aspect of each case, they may by 
rising cautiously to 2,000 or 3,000 metres lessen the 

90 



AIR HYGIENE 

force of their arterial tension; but the return to 
normal pressure is a great strain on their arteries 
and great prudence is necessary.^ Almost all the 
airmen with hypertension whom we examined during 
the war rapidly arrived at a condition of cardiac 
asthenia. We may quote the case of a captain who 
had marked hypertension before becoming a very 
active airman. Almost within a year of starting to 
fly he became subject to attacks of syncope in the 
air always during the descent and even when this 
was accomplished at a reasonable speed. During 
rest the hypertension was found to be replaced by 
extreme hypotension. We had to refuse categori- 
cally to allow him to fly. 

Let us put side by side with the above facts, 
the observations made by Mennier upon himself.^ 
He noticed an increase of pressure both of Mx. and 
Mn. during ascent and a fall of pressure during 
descent. He found changes of pressure amounting 
to 7-8 cm. for Mx. and 2, 3, 5 and even 7 cm. for 
Mn. (rapid descent). Our colleague's age (51) and 
the state of his myocardium presumably account for 
such a considerable reaction. 

Pulmonary Systems. — Every chronic lesion of the 
lungs constitutes an absolute contra-indication. 
This applies especially to asthenia, emphysema, 
pleural adhesions, and chronic bronchitis. Pulmonary 
tuberculosis is also clearly ruled out. 

The physiological condition of the lungs is esti- 
mated by the spirometer: the vital capacity so 



^ Delage communicated to the Acad^mie des Sciences on 
May 22, 191 1, the case of a young airman who experienced 
no discomfort, dizziness or obnubilation after his arterial 
pressure had been reduced from 22 to 16. 

2 Thesis of Ferry, loc. cit.^ pp. Qi-93. 

91 



AIR HYGIENE 

measured should not be less than 3,000 c.c. The 
inspiratory and expiratory pressures should also be 
observed by means of a Pachon pneumometer. 
Martin Flack has used as a measurement the length 
of time for which it is possible to hold the breath. 
In the normal person this is about sixty seconds and 
it may be reduced to fifteen or twenty seconds. 
After some exercise such as that of bending down 
and touching the toe four times in thirty seconds, 
the breath cannot be held even with a great effort 
for more than thirty seconds. 

The same author has suggested another test — that 
of holding the breath under a pressure of 40 mm. 
of Hg. A long expiration is made and is followed 
by a deep inspiration; the nose is held and a column 
of mercury 40 mm. in height has to be supported 
by the subject of the experiment. The normal 
length of endurance is forty to fifty seconds. Some- 
times the airman when fatigued cannot hold out 
more than twenty to twenty-five seconds. 

The expiratory pressure may also be measured by 
blowing, after deep inspiration, into a tube con- 
nected with a column of mercury. In asthenics and 
in untrained individuals the height to which the 
column can be raised is diminished. 

Above 2,000 metres men with chronic pulmonary 
disease become excessively short of breath. Ferry 
was acquainted with an officer, twenty-six years old, 
in whom a latent tuberculosis was aroused and its 
progress accelerated by flying. After a trip carried 
out at 2,100 metres he suffered from haemoptysis. 

Those who have been wounded in the chest should 
also be forbidden to fly. Ferry reports the case of 
a lieutenant aged twenty-six, a footballer, who had 
been wounded eight times and whose chief disable- 

92 



AIR HYGIENE 

ment was caused by a bullet which passed through 
the right lung. He learned to pilot a machine but 
could never rise above 2,000 metres, for above this 
height he became rapidly short of breath. He was 
killed by an enemy airman. 

The Auditory System. — The auditory system, by 
virtue of the fact that it is responsible for the sense 
of equihbrium, is the essential factor of aviation. 
It is only too true that a large number of accidents 
have been due to otic disorders. G. Laurens men- 
tions five airmen, amongst his patients who suffered 
from chronic otorrhoea, dizziness and buzzings. 
They were all killed as a result of the auricular 
lesions which they had concealed. 

Like stories are related by many other writers : 
A. Niedder-Semidei in Italy, McWaltef in England, 
Castex, Gezes in France. Simple plugs of wax, 
tubo-tympanic catarrh, otic sclerosis, all these 
if they are unrecognized may have serious con- 
sequences. 

M. M. Marchoux and Nepper have been particu- 
larly insistent upon the importance of naso-pharyn- 
geal lesions, even when these are slight, such as 
simple rhinitis, tonsiHtis, or the presence of adenoid 
growths. The cure of such inflammations has 
enabled a large number of airmen to return to service 
and has freed them from auditory disturbances and 
auricular pain. Gezes has shown that the airman 
must have a sufficient nasal permeability. 

There are numerous procedures by which disturb- 
ances of hearing and equihbration can be sought 
for — the signs named after Romberg, Babinski- 
Weill, Moure; induced nystagmus, &c. 

Digestive System. — Digestive troubles and 
especially gastro-intestinal atony are of no use to 

93 



AIR HYGIENE 

the airman. Nausea, vomiting and dyspeptic dis- 
turbances rapidly grow worse. Wasting becomes 
more and more extreme, and nerve force is propor- 
tionately diminished. In Gilchrist's statistics ii per 
cent, were found unfit on account of nausea and 
vomiting during flight. 

We have known experienced pilots to complain of 
vague intestinal discomfort, of colic, of pseudo- 
appendicitis and of gastric malaise — phenomena 
which are accentuated while in the air and especially 
during too rapid descent. 

The solidity of the abdominal musculature is not 
without importance. When the aeroplane is subject 
to sudden displacement the abdominal organs may 
be severely bruised, if they are not sufficiently sup- 
ported. The result may be syncope or at least 
lipothymia. 

Albuminuria is not in itself a contra-indication. 
The arterial pressure, the state of the heart and of 
the kidneys must all be taken into account. 

The Neuro-Psychic System. — It is clear that the 
examination of the nervous system must be carried 
out with the greatest care. Such diseases as tabes — 
often unnoticed — and epilepsy suffice to indicate the 
rejection of a candidate for the air service. 

The integrity of vision is equally important, not 
only the visual acuity but also the visual field, binocu- 
lar vision, and colour vision must be perfect. With 
Contounet we may also measure the speed of visual 
acuity, nocturnal vision, dazzle vision, &c. 

Since Camus and Nepper the value of a measure- 
ment of the visual auditory and tactile psycho-motor 
reactions have been greatly insisted on. These re- 
actions may in fact suffer greater or less retardation : 
for the visual over 25 hundredths of a second (in- 

94 



AIR HYGIENE 

Stead of 17-20 hundredths); for auditory and tactile 
over 20 hundredths of a second (instead of 13 to 15 
hundredths). 

In our opinion it would be a mistake to rely 
exclusively on these measurements which are sub- 
ject to errors of interpretation, and may be retarded 
in airmen who are othen\^ise excellent candidates. 
Moreover these measurements were devised a long 
time ago to study the reactions of the mentally 
deficient and their value is only relative. They may 
give useful indications in the selection of athletes, 
they allow us to watch the progress of sufferers 
from nervous fatigue, and to control training, but 
conclusions must be drawn therefrom with a wise 
prudence.^ 

Extremely interesting also is the study of reaction 
times to variations of equilibrium made by Broca, 
Maublanc and Ratie, who measured them by means 
of a special apparatus. The reaction times in normal 
subjects vary between 9 and 12 hundredths of a 
second for sagittal and transverse directions and 
between 15 and 18 hundredths of a second for the 
horizontal direction. In some people this time is 
distinctly increased, in others an error appears in 
estimating the direction of displacement. 

Aination after Recovery from Wounds. 

Although this problem has now lost its chief 
importance a few words may usefully be said 
about it. 

1 Further information concerning the organization of 
the French medical aviation centre at Louvie and on the 
methods employed there will be found in the communica- 
tion of Georges Guillain, " Examens medicaux et physio- 
logiques du personnel navigant de I'aviation," Soc, de Biol., 
session on June 21, iqiq, p. 655. 

95 



AIR HYGIENE 

It seems that those who have been wounded are 
not to be relied on as airmen. Ferry reports the 
case of an infantryman who was wounded in the 
head by a shell fragment with resulting left hemi- 
plegia and who entered the air service six months 
later. It is true that he was already a member of 
this corps in 1911. None the less he complained 
after every flight that he suffered from buzzings in 
the ears, especially in the left ear, which persisted 
day and night. After every flight too he experienced 
great fatigue, loss of memory, and imperative need 
of sleep. Another case, also quoted by Ferry, is 
that of a man who had recovered after being tre- 
panned and who suffered from transient paresis of 
arm and leg when he passed a height of 1,800 metres. 
Generally speaking all who have been wounded in 
the head ought to be rejected, especially those who 
have been trepanned. 

There are certain wound scars of the thigh or leg 
which may hinder movement as a result of cramps 
or pain, often brought on by cold. A pilot bomber, 
mentioned by Ferry, was hindered in steering by 
loss of sensation in his foot combined with paralysis 
of the extensor muscles. 

Another airman who came under Ferry's observa- 
tion was greatly troubled by a partial ankylosis of 
the hip following a fracture. True, there is the case 
of an " ace '' with a wooden leg, but it seems that 
this is not an example to be followed! 



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